RAHHH

backend/lib/python3.12/site-packages/twisted/logger/test/__init__.py

@@ -0,0 +1,7 @@
+# -*- test-case-name: twisted.logger.test -*-
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Unit tests for L{twisted.logger}.
+"""

backend/lib/python3.12/site-packages/twisted/logger/test/test_buffer.py

@@ -0,0 +1,62 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._buffer}.
+"""
+
+from typing import List, cast
+
+from zope.interface.exceptions import BrokenMethodImplementation
+from zope.interface.verify import verifyObject
+
+from twisted.trial import unittest
+from .._buffer import LimitedHistoryLogObserver
+from .._interfaces import ILogObserver, LogEvent
+
+
+class LimitedHistoryLogObserverTests(unittest.TestCase):
+    """
+    Tests for L{LimitedHistoryLogObserver}.
+    """
+
+    def test_interface(self) -> None:
+        """
+        L{LimitedHistoryLogObserver} provides L{ILogObserver}.
+        """
+        observer = LimitedHistoryLogObserver(0)
+        try:
+            verifyObject(ILogObserver, observer)
+        except BrokenMethodImplementation as e:
+            self.fail(e)
+
+    def test_order(self) -> None:
+        """
+        L{LimitedHistoryLogObserver} saves history in the order it is received.
+        """
+        size = 4
+        events = [dict(n=n) for n in range(size // 2)]
+        observer = LimitedHistoryLogObserver(size)
+
+        for event in events:
+            observer(event)
+
+        outEvents: List[LogEvent] = []
+        observer.replayTo(cast(ILogObserver, outEvents.append))
+        self.assertEqual(events, outEvents)
+
+    def test_limit(self) -> None:
+        """
+        When more events than a L{LimitedHistoryLogObserver}'s maximum size are
+        buffered, older events will be dropped.
+        """
+        size = 4
+        events = [dict(n=n) for n in range(size * 2)]
+        observer = LimitedHistoryLogObserver(size)
+
+        for event in events:
+            observer(event)
+
+        outEvents: List[LogEvent] = []
+        observer.replayTo(cast(ILogObserver, outEvents.append))
+        self.assertEqual(events[-size:], outEvents)

backend/lib/python3.12/site-packages/twisted/logger/test/test_capture.py

@@ -0,0 +1,36 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._capture}.
+"""
+
+from twisted.logger import Logger, LogLevel
+from twisted.trial.unittest import TestCase
+from .._capture import capturedLogs
+
+
+class LogCaptureTests(TestCase):
+    """
+    Tests for L{LogCaptureTests}.
+    """
+
+    log = Logger()
+
+    def test_capture(self) -> None:
+        """
+        Events logged within context are captured.
+        """
+        foo = object()
+
+        with capturedLogs() as captured:
+            self.log.debug("Capture this, please", foo=foo)
+            self.log.info("Capture this too, please", foo=foo)
+
+        self.assertTrue(len(captured) == 2)
+        self.assertEqual(captured[0]["log_format"], "Capture this, please")
+        self.assertEqual(captured[0]["log_level"], LogLevel.debug)
+        self.assertEqual(captured[0]["foo"], foo)
+        self.assertEqual(captured[1]["log_format"], "Capture this too, please")
+        self.assertEqual(captured[1]["log_level"], LogLevel.info)
+        self.assertEqual(captured[1]["foo"], foo)

backend/lib/python3.12/site-packages/twisted/logger/test/test_file.py

@@ -0,0 +1,184 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._file}.
+"""
+
+from io import StringIO
+from types import TracebackType
+from typing import IO, Any, AnyStr, Optional, Type, cast
+
+from zope.interface.exceptions import BrokenMethodImplementation
+from zope.interface.verify import verifyObject
+
+from twisted.python.failure import Failure
+from twisted.trial.unittest import TestCase
+from .._file import FileLogObserver, textFileLogObserver
+from .._interfaces import ILogObserver
+
+
+class FileLogObserverTests(TestCase):
+    """
+    Tests for L{FileLogObserver}.
+    """
+
+    def test_interface(self) -> None:
+        """
+        L{FileLogObserver} is an L{ILogObserver}.
+        """
+        with StringIO() as fileHandle:
+            observer = FileLogObserver(fileHandle, lambda e: str(e))
+            try:
+                verifyObject(ILogObserver, observer)
+            except BrokenMethodImplementation as e:
+                self.fail(e)
+
+    def test_observeWrites(self) -> None:
+        """
+        L{FileLogObserver} writes to the given file when it observes events.
+        """
+        with StringIO() as fileHandle:
+            observer = FileLogObserver(fileHandle, lambda e: str(e))
+            event = dict(x=1)
+            observer(event)
+            self.assertEqual(fileHandle.getvalue(), str(event))
+
+    def _test_observeWrites(self, what: Optional[str], count: int) -> None:
+        """
+        Verify that observer performs an expected number of writes when the
+        formatter returns a given value.
+
+        @param what: the value for the formatter to return.
+        @param count: the expected number of writes.
+        """
+        with DummyFile() as fileHandle:
+            observer = FileLogObserver(cast(IO[Any], fileHandle), lambda e: what)
+            event = dict(x=1)
+            observer(event)
+            self.assertEqual(fileHandle.writes, count)
+
+    def test_observeWritesNone(self) -> None:
+        """
+        L{FileLogObserver} does not write to the given file when it observes
+        events and C{formatEvent} returns L{None}.
+        """
+        self._test_observeWrites(None, 0)
+
+    def test_observeWritesEmpty(self) -> None:
+        """
+        L{FileLogObserver} does not write to the given file when it observes
+        events and C{formatEvent} returns C{""}.
+        """
+        self._test_observeWrites("", 0)
+
+    def test_observeFlushes(self) -> None:
+        """
+        L{FileLogObserver} calles C{flush()} on the output file when it
+        observes an event.
+        """
+        with DummyFile() as fileHandle:
+            observer = FileLogObserver(cast(IO[Any], fileHandle), lambda e: str(e))
+            event = dict(x=1)
+            observer(event)
+            self.assertEqual(fileHandle.flushes, 1)
+
+
+class TextFileLogObserverTests(TestCase):
+    """
+    Tests for L{textFileLogObserver}.
+    """
+
+    def test_returnsFileLogObserver(self) -> None:
+        """
+        L{textFileLogObserver} returns a L{FileLogObserver}.
+        """
+        with StringIO() as fileHandle:
+            observer = textFileLogObserver(fileHandle)
+            self.assertIsInstance(observer, FileLogObserver)
+
+    def test_outFile(self) -> None:
+        """
+        Returned L{FileLogObserver} has the correct outFile.
+        """
+        with StringIO() as fileHandle:
+            observer = textFileLogObserver(fileHandle)
+            self.assertIs(observer._outFile, fileHandle)
+
+    def test_timeFormat(self) -> None:
+        """
+        Returned L{FileLogObserver} has the correct outFile.
+        """
+        with StringIO() as fileHandle:
+            observer = textFileLogObserver(fileHandle, timeFormat="%f")
+            observer(dict(log_format="XYZZY", log_time=112345.6))
+            self.assertEqual(fileHandle.getvalue(), "600000 [-#-] XYZZY\n")
+
+    def test_observeFailure(self) -> None:
+        """
+        If the C{"log_failure"} key exists in an event, the observer appends
+        the failure's traceback to the output.
+        """
+        with StringIO() as fileHandle:
+            observer = textFileLogObserver(fileHandle)
+
+            try:
+                1 / 0
+            except ZeroDivisionError:
+                failure = Failure()
+
+            event = dict(log_failure=failure)
+            observer(event)
+            output = fileHandle.getvalue()
+            self.assertTrue(
+                output.split("\n")[1].startswith("\tTraceback "), msg=repr(output)
+            )
+
+    def test_observeFailureThatRaisesInGetTraceback(self) -> None:
+        """
+        If the C{"log_failure"} key exists in an event, and contains an object
+        that raises when you call its C{getTraceback()}, then the observer
+        appends a message noting the problem, instead of raising.
+        """
+        with StringIO() as fileHandle:
+            observer = textFileLogObserver(fileHandle)
+            event = dict(log_failure=object())  # object has no getTraceback()
+            observer(event)
+            output = fileHandle.getvalue()
+            expected = "(UNABLE TO OBTAIN TRACEBACK FROM EVENT)"
+            self.assertIn(expected, output)
+
+
+class DummyFile:
+    """
+    File that counts writes and flushes.
+    """
+
+    def __init__(self) -> None:
+        self.writes = 0
+        self.flushes = 0
+
+    def write(self, data: AnyStr) -> None:
+        """
+        Write data.
+
+        @param data: data
+        """
+        self.writes += 1
+
+    def flush(self) -> None:
+        """
+        Flush buffers.
+        """
+        self.flushes += 1
+
+    def __enter__(self) -> "DummyFile":
+        return self
+
+    def __exit__(
+        self,
+        exc_type: Optional[Type[BaseException]],
+        exc_value: Optional[BaseException],
+        traceback: Optional[TracebackType],
+    ) -> Optional[bool]:
+        pass

backend/lib/python3.12/site-packages/twisted/logger/test/test_filter.py

@@ -0,0 +1,393 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._filter}.
+"""
+
+from typing import Iterable, List, Tuple, Union, cast
+
+from zope.interface import implementer
+from zope.interface.exceptions import BrokenMethodImplementation
+from zope.interface.verify import verifyObject
+
+from constantly import NamedConstant
+
+from twisted.trial import unittest
+from .._filter import (
+    FilteringLogObserver,
+    ILogFilterPredicate,
+    LogLevelFilterPredicate,
+    PredicateResult,
+)
+from .._interfaces import ILogObserver, LogEvent
+from .._levels import InvalidLogLevelError, LogLevel
+from .._observer import LogPublisher, bitbucketLogObserver
+
+
+class FilteringLogObserverTests(unittest.TestCase):
+    """
+    Tests for L{FilteringLogObserver}.
+    """
+
+    def test_interface(self) -> None:
+        """
+        L{FilteringLogObserver} is an L{ILogObserver}.
+        """
+        observer = FilteringLogObserver(cast(ILogObserver, lambda e: None), ())
+        try:
+            verifyObject(ILogObserver, observer)
+        except BrokenMethodImplementation as e:
+            self.fail(e)
+
+    def filterWith(
+        self, filters: Iterable[str], other: bool = False
+    ) -> Union[List[int], Tuple[List[int], List[int]]]:
+        """
+        Apply a set of pre-defined filters on a known set of events and return
+        the filtered list of event numbers.
+
+        The pre-defined events are four events with a C{count} attribute set to
+        C{0}, C{1}, C{2}, and C{3}.
+
+        @param filters: names of the filters to apply.
+            Options are:
+                - C{"twoMinus"} (count <=2),
+                - C{"twoPlus"} (count >= 2),
+                - C{"notTwo"} (count != 2),
+                - C{"no"} (False).
+        @param other: Whether to return a list of filtered events as well.
+
+        @return: event numbers or 2-tuple of lists of event numbers.
+        """
+        events: List[LogEvent] = [
+            dict(count=0),
+            dict(count=1),
+            dict(count=2),
+            dict(count=3),
+        ]
+
+        class Filters:
+            @staticmethod
+            def twoMinus(event: LogEvent) -> NamedConstant:
+                """
+                count <= 2
+
+                @param event: an event
+
+                @return: L{PredicateResult.yes} if C{event["count"] <= 2},
+                    otherwise L{PredicateResult.maybe}.
+                """
+                if event["count"] <= 2:
+                    return PredicateResult.yes
+                return PredicateResult.maybe
+
+            @staticmethod
+            def twoPlus(event: LogEvent) -> NamedConstant:
+                """
+                count >= 2
+
+                @param event: an event
+
+                @return: L{PredicateResult.yes} if C{event["count"] >= 2},
+                    otherwise L{PredicateResult.maybe}.
+                """
+                if event["count"] >= 2:
+                    return PredicateResult.yes
+                return PredicateResult.maybe
+
+            @staticmethod
+            def notTwo(event: LogEvent) -> NamedConstant:
+                """
+                count != 2
+
+                @param event: an event
+
+                @return: L{PredicateResult.yes} if C{event["count"] != 2},
+                    otherwise L{PredicateResult.maybe}.
+                """
+                if event["count"] == 2:
+                    return PredicateResult.no
+                return PredicateResult.maybe
+
+            @staticmethod
+            def no(event: LogEvent) -> NamedConstant:
+                """
+                No way, man.
+
+                @param event: an event
+
+                @return: L{PredicateResult.no}
+                """
+                return PredicateResult.no
+
+            @staticmethod
+            def bogus(event: LogEvent) -> NamedConstant:
+                """
+                Bogus result.
+
+                @param event: an event
+
+                @return: something other than a valid predicate result.
+                """
+                return None
+
+        predicates = (getattr(Filters, f) for f in filters)
+        eventsSeen: List[LogEvent] = []
+        eventsNotSeen: List[LogEvent] = []
+        trackingObserver = cast(ILogObserver, eventsSeen.append)
+
+        if other:
+            negativeObserver = cast(ILogObserver, eventsNotSeen.append)
+        else:
+            negativeObserver = bitbucketLogObserver
+
+        filteringObserver = FilteringLogObserver(
+            trackingObserver, predicates, negativeObserver
+        )
+
+        for e in events:
+            filteringObserver(e)
+
+        if other:
+            return (
+                [cast(int, e["count"]) for e in eventsSeen],
+                [cast(int, e["count"]) for e in eventsNotSeen],
+            )
+        else:
+            return [cast(int, e["count"]) for e in eventsSeen]
+
+    def test_shouldLogEventNoFilters(self) -> None:
+        """
+        No filters: all events come through.
+        """
+        self.assertEqual(self.filterWith([]), [0, 1, 2, 3])
+
+    def test_shouldLogEventNoFilter(self) -> None:
+        """
+        Filter with negative predicate result.
+        """
+        self.assertEqual(self.filterWith(["notTwo"]), [0, 1, 3])
+
+    def test_shouldLogEventOtherObserver(self) -> None:
+        """
+        Filtered results get sent to the other observer, if passed.
+        """
+        self.assertEqual(self.filterWith(["notTwo"], True), ([0, 1, 3], [2]))
+
+    def test_shouldLogEventYesFilter(self) -> None:
+        """
+        Filter with positive predicate result.
+        """
+        self.assertEqual(self.filterWith(["twoPlus"]), [0, 1, 2, 3])
+
+    def test_shouldLogEventYesNoFilter(self) -> None:
+        """
+        Series of filters with positive and negative predicate results.
+        """
+        self.assertEqual(self.filterWith(["twoPlus", "no"]), [2, 3])
+
+    def test_shouldLogEventYesYesNoFilter(self) -> None:
+        """
+        Series of filters with positive, positive and negative predicate
+        results.
+        """
+        self.assertEqual(self.filterWith(["twoPlus", "twoMinus", "no"]), [0, 1, 2, 3])
+
+    def test_shouldLogEventBadPredicateResult(self) -> None:
+        """
+        Filter with invalid predicate result.
+        """
+        self.assertRaises(TypeError, self.filterWith, ["bogus"])
+
+    def test_call(self) -> None:
+        """
+        Test filtering results from each predicate type.
+        """
+        e: LogEvent = dict(obj=object())
+
+        def callWithPredicateResult(result: NamedConstant) -> List[LogEvent]:
+            seen: List[LogEvent] = []
+            observer = FilteringLogObserver(
+                cast(ILogObserver, lambda e: seen.append(e)),
+                (cast(ILogFilterPredicate, lambda e: result),),
+            )
+            observer(e)
+            return seen
+
+        self.assertIn(e, callWithPredicateResult(PredicateResult.yes))
+        self.assertIn(e, callWithPredicateResult(PredicateResult.maybe))
+        self.assertNotIn(e, callWithPredicateResult(PredicateResult.no))
+
+    def test_trace(self) -> None:
+        """
+        Tracing keeps track of forwarding through the filtering observer.
+        """
+        event: LogEvent = dict(log_trace=[])
+
+        oYes = cast(ILogObserver, lambda e: None)
+        oNo = cast(ILogObserver, lambda e: None)
+
+        @implementer(ILogObserver)
+        def testObserver(e: LogEvent) -> None:
+            self.assertIs(e, event)
+            self.assertEqual(
+                event["log_trace"],
+                [
+                    (publisher, yesFilter),
+                    (yesFilter, oYes),
+                    (publisher, noFilter),
+                    # ... noFilter doesn't call oNo
+                    (publisher, oTest),
+                ],
+            )
+
+        oTest = testObserver
+
+        yesFilter = FilteringLogObserver(
+            oYes, (cast(ILogFilterPredicate, lambda e: PredicateResult.yes),)
+        )
+        noFilter = FilteringLogObserver(
+            oNo, (cast(ILogFilterPredicate, lambda e: PredicateResult.no),)
+        )
+
+        publisher = LogPublisher(yesFilter, noFilter, testObserver)
+        publisher(event)
+
+
+class LogLevelFilterPredicateTests(unittest.TestCase):
+    """
+    Tests for L{LogLevelFilterPredicate}.
+    """
+
+    def test_defaultLogLevel(self) -> None:
+        """
+        Default log level is used.
+        """
+        predicate = LogLevelFilterPredicate()
+
+        # Test using both "" and None as default namespace, because None was the
+        # documented default value in the past.
+
+        for default in ("", cast(str, None)):
+            self.assertEqual(
+                predicate.logLevelForNamespace(default), predicate.defaultLogLevel
+            )
+            self.assertEqual(
+                predicate.logLevelForNamespace("rocker.cool.namespace"),
+                predicate.defaultLogLevel,
+            )
+
+    def test_setLogLevel(self) -> None:
+        """
+        Setting and retrieving log levels.
+        """
+        predicate = LogLevelFilterPredicate()
+
+        # Test using both "" and None as default namespace, because None was the
+        # documented default value in the past.
+
+        for default in ("", cast(str, None)):
+            predicate.setLogLevelForNamespace(default, LogLevel.error)
+            predicate.setLogLevelForNamespace("twext.web2", LogLevel.debug)
+            predicate.setLogLevelForNamespace("twext.web2.dav", LogLevel.warn)
+
+            self.assertEqual(predicate.logLevelForNamespace(""), LogLevel.error)
+            self.assertEqual(
+                predicate.logLevelForNamespace(cast(str, None)), LogLevel.error
+            )
+            self.assertEqual(predicate.logLevelForNamespace("twisted"), LogLevel.error)
+            self.assertEqual(
+                predicate.logLevelForNamespace("twext.web2"), LogLevel.debug
+            )
+            self.assertEqual(
+                predicate.logLevelForNamespace("twext.web2.dav"), LogLevel.warn
+            )
+            self.assertEqual(
+                predicate.logLevelForNamespace("twext.web2.dav.test"), LogLevel.warn
+            )
+            self.assertEqual(
+                predicate.logLevelForNamespace("twext.web2.dav.test1.test2"),
+                LogLevel.warn,
+            )
+
+    def test_setInvalidLogLevel(self) -> None:
+        """
+        Can't pass invalid log levels to C{setLogLevelForNamespace()}.
+        """
+        predicate = LogLevelFilterPredicate()
+
+        self.assertRaises(
+            InvalidLogLevelError,
+            predicate.setLogLevelForNamespace,
+            "twext.web2",
+            object(),
+        )
+
+        # Level must be a constant, not the name of a constant
+        self.assertRaises(
+            InvalidLogLevelError,
+            predicate.setLogLevelForNamespace,
+            "twext.web2",
+            "debug",
+        )
+
+    def test_clearLogLevels(self) -> None:
+        """
+        Clearing log levels.
+        """
+        predicate = LogLevelFilterPredicate()
+
+        predicate.setLogLevelForNamespace("twext.web2", LogLevel.debug)
+        predicate.setLogLevelForNamespace("twext.web2.dav", LogLevel.error)
+
+        predicate.clearLogLevels()
+
+        self.assertEqual(
+            predicate.logLevelForNamespace("twisted"), predicate.defaultLogLevel
+        )
+        self.assertEqual(
+            predicate.logLevelForNamespace("twext.web2"), predicate.defaultLogLevel
+        )
+        self.assertEqual(
+            predicate.logLevelForNamespace("twext.web2.dav"), predicate.defaultLogLevel
+        )
+        self.assertEqual(
+            predicate.logLevelForNamespace("twext.web2.dav.test"),
+            predicate.defaultLogLevel,
+        )
+        self.assertEqual(
+            predicate.logLevelForNamespace("twext.web2.dav.test1.test2"),
+            predicate.defaultLogLevel,
+        )
+
+    def test_filtering(self) -> None:
+        """
+        Events are filtered based on log level/namespace.
+        """
+        predicate = LogLevelFilterPredicate()
+
+        predicate.setLogLevelForNamespace("", LogLevel.error)
+        predicate.setLogLevelForNamespace("twext.web2", LogLevel.debug)
+        predicate.setLogLevelForNamespace("twext.web2.dav", LogLevel.warn)
+
+        def checkPredicate(
+            namespace: str, level: NamedConstant, expectedResult: NamedConstant
+        ) -> None:
+            event: LogEvent = dict(log_namespace=namespace, log_level=level)
+            self.assertEqual(expectedResult, predicate(event))
+
+        checkPredicate("", LogLevel.debug, PredicateResult.no)
+        checkPredicate(cast(str, None), LogLevel.debug, PredicateResult.no)
+        checkPredicate("", LogLevel.error, PredicateResult.no)
+        checkPredicate(cast(str, None), LogLevel.error, PredicateResult.no)
+
+        checkPredicate("twext.web2", LogLevel.debug, PredicateResult.maybe)
+        checkPredicate("twext.web2", LogLevel.error, PredicateResult.maybe)
+
+        checkPredicate("twext.web2.dav", LogLevel.debug, PredicateResult.no)
+        checkPredicate("twext.web2.dav", LogLevel.error, PredicateResult.maybe)
+
+        checkPredicate("", LogLevel.critical, PredicateResult.no)
+        checkPredicate(cast(str, None), LogLevel.critical, PredicateResult.no)
+        checkPredicate("twext.web2", None, PredicateResult.no)

backend/lib/python3.12/site-packages/twisted/logger/test/test_flatten.py

@@ -0,0 +1,326 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._format}.
+"""
+
+import json
+from itertools import count
+from typing import Any, Callable, Optional
+
+try:
+    from time import tzset
+except ImportError:
+    tzset = None  # type: ignore[assignment]
+
+from twisted.trial import unittest
+from .._flatten import KeyFlattener, aFormatter, extractField, flattenEvent
+from .._format import formatEvent
+from .._interfaces import LogEvent
+
+
+class FlatFormattingTests(unittest.TestCase):
+    """
+    Tests for flattened event formatting functions.
+    """
+
+    def test_formatFlatEvent(self) -> None:
+        """
+        L{flattenEvent} will "flatten" an event so that, if scrubbed of all but
+        serializable objects, it will preserve all necessary data to be
+        formatted once serialized.  When presented with an event thusly
+        flattened, L{formatEvent} will produce the same output.
+        """
+        counter = count()
+
+        class Ephemeral:
+            attribute = "value"
+
+        event1 = dict(
+            log_format=(
+                "callable: {callme()} "
+                "attribute: {object.attribute} "
+                "numrepr: {number!r} "
+                "numstr: {number!s} "
+                "strrepr: {string!r} "
+                "unistr: {unistr!s}"
+            ),
+            callme=lambda: next(counter),
+            object=Ephemeral(),
+            number=7,
+            string="hello",
+            unistr="ö",
+        )
+
+        flattenEvent(event1)
+
+        event2 = dict(event1)
+        del event2["callme"]
+        del event2["object"]
+        event3 = json.loads(json.dumps(event2))
+        self.assertEqual(
+            formatEvent(event3),
+            (
+                "callable: 0 "
+                "attribute: value "
+                "numrepr: 7 "
+                "numstr: 7 "
+                "strrepr: 'hello' "
+                "unistr: ö"
+            ),
+        )
+
+    def test_formatFlatEventBadFormat(self) -> None:
+        """
+        If the format string is invalid, an error is produced.
+        """
+        event1 = dict(
+            log_format=("strrepr: {string!X}"),
+            string="hello",
+        )
+
+        flattenEvent(event1)
+        event2 = json.loads(json.dumps(event1))
+
+        self.assertTrue(formatEvent(event2).startswith("Unable to format event"))
+
+    def test_formatFlatEventWithMutatedFields(self) -> None:
+        """
+        L{formatEvent} will prefer the stored C{str()} or C{repr()} value for
+        an object, in case the other version.
+        """
+
+        class Unpersistable:
+            """
+            Unpersitable object.
+            """
+
+            destructed = False
+
+            def selfDestruct(self) -> None:
+                """
+                Self destruct.
+                """
+                self.destructed = True
+
+            def __repr__(self) -> str:
+                if self.destructed:
+                    return "post-serialization garbage"
+                else:
+                    return "un-persistable"
+
+        up = Unpersistable()
+        event1 = dict(log_format="unpersistable: {unpersistable}", unpersistable=up)
+
+        flattenEvent(event1)
+        up.selfDestruct()
+
+        self.assertEqual(formatEvent(event1), "unpersistable: un-persistable")
+
+    def test_keyFlattening(self) -> None:
+        """
+        Test that L{KeyFlattener.flatKey} returns the expected keys for format
+        fields.
+        """
+
+        def keyFromFormat(format: str) -> str:
+            for (
+                literalText,
+                fieldName,
+                formatSpec,
+                conversion,
+            ) in aFormatter.parse(format):
+                assert fieldName is not None
+                return KeyFlattener().flatKey(fieldName, formatSpec, conversion)
+            assert False, "Unable to derive key from format: {format}"
+
+        # No name
+        try:
+            self.assertEqual(keyFromFormat("{}"), "!:")
+        except ValueError:
+            # In python 2.6, an empty field name causes Formatter.parse to
+            # raise ValueError.
+            # In Python 2.7, it's allowed, so this exception is unexpected.
+            raise
+
+        # Just a name
+        self.assertEqual(keyFromFormat("{foo}"), "foo!:")
+
+        # Add conversion
+        self.assertEqual(keyFromFormat("{foo!s}"), "foo!s:")
+        self.assertEqual(keyFromFormat("{foo!r}"), "foo!r:")
+
+        # Add format spec
+        self.assertEqual(keyFromFormat("{foo:%s}"), "foo!:%s")
+        self.assertEqual(keyFromFormat("{foo:!}"), "foo!:!")
+        self.assertEqual(keyFromFormat("{foo::}"), "foo!::")
+
+        # Both
+        self.assertEqual(keyFromFormat("{foo!s:%s}"), "foo!s:%s")
+        self.assertEqual(keyFromFormat("{foo!s:!}"), "foo!s:!")
+        self.assertEqual(keyFromFormat("{foo!s::}"), "foo!s::")
+
+        sameFlattener = KeyFlattener()
+        (
+            (
+                literalText,
+                fieldName,
+                formatSpec,
+                conversion,
+            ),
+        ) = aFormatter.parse("{x}")
+        assert fieldName is not None
+
+        self.assertEqual(
+            sameFlattener.flatKey(fieldName, formatSpec, conversion), "x!:"
+        )
+        self.assertEqual(
+            sameFlattener.flatKey(fieldName, formatSpec, conversion), "x!:/2"
+        )
+
+    def _test_formatFlatEvent_fieldNamesSame(
+        self, event: Optional[LogEvent] = None
+    ) -> LogEvent:
+        """
+        The same format field used twice in one event is rendered twice.
+
+        @param event: An event to flatten.  If L{None}, create a new event.
+        @return: C{event} or the event created.
+        """
+        if event is None:
+            counter = count()
+
+            class CountStr:
+                """
+                Hack
+                """
+
+                def __str__(self) -> str:
+                    return str(next(counter))
+
+            event = dict(
+                log_format="{x} {x}",
+                x=CountStr(),
+            )
+
+        flattenEvent(event)
+        self.assertEqual(formatEvent(event), "0 1")
+
+        return event
+
+    def test_formatFlatEventFieldNamesSame(self) -> None:
+        """
+        The same format field used twice in one event is rendered twice.
+        """
+        self._test_formatFlatEvent_fieldNamesSame()
+
+    def test_formatFlatEventFieldNamesSameAgain(self) -> None:
+        """
+        The same event flattened twice gives the same (already rendered)
+        result.
+        """
+        event = self._test_formatFlatEvent_fieldNamesSame()
+        self._test_formatFlatEvent_fieldNamesSame(event)
+
+    def test_formatEventFlatTrailingText(self) -> None:
+        """
+        L{formatEvent} will handle a flattened event with tailing text after
+        a replacement field.
+        """
+        event = dict(
+            log_format="test {x} trailing",
+            x="value",
+        )
+        flattenEvent(event)
+
+        result = formatEvent(event)
+
+        self.assertEqual(result, "test value trailing")
+
+    def test_extractField(
+        self, flattenFirst: Callable[[LogEvent], LogEvent] = lambda x: x
+    ) -> None:
+        """
+        L{extractField} will extract a field used in the format string.
+
+        @param flattenFirst: callable to flatten an event
+        """
+
+        class ObjectWithRepr:
+            def __repr__(self) -> str:
+                return "repr"
+
+        class Something:
+            def __init__(self) -> None:
+                self.number = 7
+                self.object = ObjectWithRepr()
+
+            def __getstate__(self) -> None:
+                raise NotImplementedError("Just in case.")
+
+        event = dict(
+            log_format="{something.number} {something.object}",
+            something=Something(),
+        )
+
+        flattened = flattenFirst(event)
+
+        def extract(field: str) -> Any:
+            return extractField(field, flattened)
+
+        self.assertEqual(extract("something.number"), 7)
+        self.assertEqual(extract("something.number!s"), "7")
+        self.assertEqual(extract("something.object!s"), "repr")
+
+    def test_extractFieldFlattenFirst(self) -> None:
+        """
+        L{extractField} behaves identically if the event is explicitly
+        flattened first.
+        """
+
+        def flattened(event: LogEvent) -> LogEvent:
+            flattenEvent(event)
+            return event
+
+        self.test_extractField(flattened)
+
+    def test_flattenEventWithoutFormat(self) -> None:
+        """
+        L{flattenEvent} will do nothing to an event with no format string.
+        """
+        inputEvent = {"a": "b", "c": 1}
+        flattenEvent(inputEvent)
+        self.assertEqual(inputEvent, {"a": "b", "c": 1})
+
+    def test_flattenEventWithInertFormat(self) -> None:
+        """
+        L{flattenEvent} will do nothing to an event with a format string that
+        contains no format fields.
+        """
+        inputEvent = {"a": "b", "c": 1, "log_format": "simple message"}
+        flattenEvent(inputEvent)
+        self.assertEqual(
+            inputEvent,
+            {
+                "a": "b",
+                "c": 1,
+                "log_format": "simple message",
+            },
+        )
+
+    def test_flattenEventWithNoneFormat(self) -> None:
+        """
+        L{flattenEvent} will do nothing to an event with log_format set to
+        None.
+        """
+        inputEvent = {"a": "b", "c": 1, "log_format": None}
+        flattenEvent(inputEvent)
+        self.assertEqual(
+            inputEvent,
+            {
+                "a": "b",
+                "c": 1,
+                "log_format": None,
+            },
+        )

backend/lib/python3.12/site-packages/twisted/logger/test/test_format.py

@@ -0,0 +1,732 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._format}.
+"""
+
+from typing import Any, AnyStr, Dict, Optional, cast
+
+try:
+    from time import tzset
+
+    # We should upgrade to a version of pyflakes that does not require this.
+    tzset
+except ImportError:
+    tzset = None  # type: ignore[assignment]
+
+from twisted.python.failure import Failure
+from twisted.python.test.test_tzhelper import addTZCleanup, mktime, setTZ
+from twisted.trial import unittest
+from twisted.trial.unittest import SkipTest
+from .._format import (
+    eventAsText,
+    formatEvent,
+    formatEventAsClassicLogText,
+    formatTime,
+    formatUnformattableEvent,
+    formatWithCall,
+)
+from .._interfaces import LogEvent
+from .._levels import LogLevel
+
+
+class FormattingTests(unittest.TestCase):
+    """
+    Tests for basic event formatting functions.
+    """
+
+    def format(self, logFormat: AnyStr, **event: object) -> str:
+        """
+        Create a Twisted log event dictionary from C{event} with the given
+        C{logFormat} format string, format it with L{formatEvent}, ensure that
+        its type is L{str}, and return its result.
+        """
+        event["log_format"] = logFormat
+        result = formatEvent(event)
+        self.assertIs(type(result), str)
+        return result
+
+    def test_formatEvent(self) -> None:
+        """
+        L{formatEvent} will format an event according to several rules:
+
+            - A string with no formatting instructions will be passed straight
+              through.
+
+            - PEP 3101 strings will be formatted using the keys and values of
+              the event as named fields.
+
+            - PEP 3101 keys ending with C{()} will be treated as instructions
+              to call that key (which ought to be a callable) before
+              formatting.
+
+        L{formatEvent} will always return L{str}, and if given bytes, will
+        always treat its format string as UTF-8 encoded.
+        """
+        self.assertEqual("", self.format(b""))
+        self.assertEqual("", self.format(""))
+        self.assertEqual("abc", self.format("{x}", x="abc"))
+        self.assertEqual(
+            "no, yes.",
+            self.format(
+                "{not_called}, {called()}.", not_called="no", called=lambda: "yes"
+            ),
+        )
+        self.assertEqual("S\xe1nchez", self.format(b"S\xc3\xa1nchez"))
+        self.assertIn("Unable to format event", self.format(b"S\xe1nchez"))
+        maybeResult = self.format(b"S{a!s}nchez", a=b"\xe1")
+        self.assertIn("Sb'\\xe1'nchez", maybeResult)
+
+        xe1 = str(repr(b"\xe1"))
+        self.assertIn("S" + xe1 + "nchez", self.format(b"S{a!r}nchez", a=b"\xe1"))
+
+    def test_formatMethod(self) -> None:
+        """
+        L{formatEvent} will format PEP 3101 keys containing C{.}s ending with
+        C{()} as methods.
+        """
+
+        class World:
+            def where(self) -> str:
+                return "world"
+
+        self.assertEqual(
+            "hello world", self.format("hello {what.where()}", what=World())
+        )
+
+    def test_formatAttributeSubscript(self) -> None:
+        """
+        L{formatEvent} will format subscripts of attributes per PEP 3101.
+        """
+
+        class Example(object):
+            config: Dict[str, str] = dict(foo="bar", baz="qux")
+
+        self.assertEqual(
+            "bar qux",
+            self.format(
+                "{example.config[foo]} {example.config[baz]}",
+                example=Example(),
+            ),
+        )
+
+    def test_formatEventNoFormat(self) -> None:
+        """
+        Formatting an event with no format.
+        """
+        event = dict(foo=1, bar=2)
+        result = formatEvent(event)
+
+        self.assertEqual("", result)
+
+    def test_formatEventWeirdFormat(self) -> None:
+        """
+        Formatting an event with a bogus format.
+        """
+        event = dict(log_format=object(), foo=1, bar=2)
+        result = formatEvent(event)
+
+        self.assertIn("Log format must be str", result)
+        self.assertIn(repr(event), result)
+
+    def test_formatUnformattableEvent(self) -> None:
+        """
+        Formatting an event that's just plain out to get us.
+        """
+        event = dict(log_format="{evil()}", evil=lambda: 1 / 0)
+        result = formatEvent(event)
+
+        self.assertIn("Unable to format event", result)
+        self.assertIn(repr(event), result)
+
+    def test_formatUnformattableEventWithUnformattableKey(self) -> None:
+        """
+        Formatting an unformattable event that has an unformattable key.
+        """
+        event: LogEvent = {
+            "log_format": "{evil()}",
+            "evil": lambda: 1 / 0,
+            cast(str, Unformattable()): "gurk",
+        }
+        result = formatEvent(event)
+        self.assertIn("MESSAGE LOST: unformattable object logged:", result)
+        self.assertIn("Recoverable data:", result)
+        self.assertIn("Exception during formatting:", result)
+
+    def test_formatUnformattableEventWithUnformattableValue(self) -> None:
+        """
+        Formatting an unformattable event that has an unformattable value.
+        """
+        event = dict(
+            log_format="{evil()}",
+            evil=lambda: 1 / 0,
+            gurk=Unformattable(),
+        )
+        result = formatEvent(event)
+        self.assertIn("MESSAGE LOST: unformattable object logged:", result)
+        self.assertIn("Recoverable data:", result)
+        self.assertIn("Exception during formatting:", result)
+
+    def test_formatUnformattableEventWithUnformattableErrorOMGWillItStop(self) -> None:
+        """
+        Formatting an unformattable event that has an unformattable value.
+        """
+        event = dict(
+            log_format="{evil()}",
+            evil=lambda: 1 / 0,
+            recoverable="okay",
+        )
+        # Call formatUnformattableEvent() directly with a bogus exception.
+        result = formatUnformattableEvent(event, cast(BaseException, Unformattable()))
+        self.assertIn("MESSAGE LOST: unformattable object logged:", result)
+        self.assertIn(repr("recoverable") + " = " + repr("okay"), result)
+
+
+class TimeFormattingTests(unittest.TestCase):
+    """
+    Tests for time formatting functions.
+    """
+
+    def setUp(self) -> None:
+        addTZCleanup(self)
+
+    def test_formatTimeWithDefaultFormat(self) -> None:
+        """
+        Default time stamp format is RFC 3339 and offset respects the timezone
+        as set by the standard C{TZ} environment variable and L{tzset} API.
+        """
+        if tzset is None:
+            raise SkipTest("Platform cannot change timezone; unable to verify offsets.")
+
+        def testForTimeZone(
+            name: str, expectedDST: Optional[str], expectedSTD: str
+        ) -> None:
+            setTZ(name)
+
+            localSTD = mktime((2007, 1, 31, 0, 0, 0, 2, 31, 0))
+            self.assertEqual(formatTime(localSTD), expectedSTD)
+
+            if expectedDST:
+                localDST = mktime((2006, 6, 30, 0, 0, 0, 4, 181, 1))
+                self.assertEqual(formatTime(localDST), expectedDST)
+
+        # UTC
+        testForTimeZone(
+            "UTC+00",
+            None,
+            "2007-01-31T00:00:00+0000",
+        )
+
+        # West of UTC
+        testForTimeZone(
+            "EST+05EDT,M4.1.0,M10.5.0",
+            "2006-06-30T00:00:00-0400",
+            "2007-01-31T00:00:00-0500",
+        )
+
+        # East of UTC
+        testForTimeZone(
+            "CEST-01CEDT,M4.1.0,M10.5.0",
+            "2006-06-30T00:00:00+0200",
+            "2007-01-31T00:00:00+0100",
+        )
+
+        # No DST
+        testForTimeZone(
+            "CST+06",
+            None,
+            "2007-01-31T00:00:00-0600",
+        )
+
+    def test_formatTimeWithNoTime(self) -> None:
+        """
+        If C{when} argument is L{None}, we get the default output.
+        """
+        self.assertEqual(formatTime(None), "-")
+        self.assertEqual(formatTime(None, default="!"), "!")
+
+    def test_formatTimeWithNoFormat(self) -> None:
+        """
+        If C{timeFormat} argument is L{None}, we get the default output.
+        """
+        t = mktime((2013, 9, 24, 11, 40, 47, 1, 267, -1))
+        self.assertEqual(formatTime(t, timeFormat=None), "-")
+        self.assertEqual(formatTime(t, timeFormat=None, default="!"), "!")
+
+    def test_formatTimeWithAlternateTimeFormat(self) -> None:
+        """
+        Alternate time format in output.
+        """
+        t = mktime((2013, 9, 24, 11, 40, 47, 1, 267, -1))
+        self.assertEqual(formatTime(t, timeFormat="%Y/%W"), "2013/38")
+
+    def test_formatTimePercentF(self) -> None:
+        """
+        "%f" supported in time format.
+        """
+        self.assertEqual(formatTime(1000000.23456, timeFormat="%f"), "234560")
+
+
+class ClassicLogFormattingTests(unittest.TestCase):
+    """
+    Tests for classic text log event formatting functions.
+    """
+
+    def test_formatTimeDefault(self) -> None:
+        """
+        Time is first field.  Default time stamp format is RFC 3339 and offset
+        respects the timezone as set by the standard C{TZ} environment variable
+        and L{tzset} API.
+        """
+        if tzset is None:
+            raise SkipTest("Platform cannot change timezone; unable to verify offsets.")
+
+        addTZCleanup(self)
+        setTZ("UTC+00")
+
+        t = mktime((2013, 9, 24, 11, 40, 47, 1, 267, -1))
+        event = dict(log_format="XYZZY", log_time=t)
+        self.assertEqual(
+            formatEventAsClassicLogText(event),
+            "2013-09-24T11:40:47+0000 [-\x23-] XYZZY\n",
+        )
+
+    def test_formatTimeCustom(self) -> None:
+        """
+        Time is first field.  Custom formatting function is an optional
+        argument.
+        """
+
+        def formatTime(t: Optional[float]) -> str:
+            return f"__{t}__"
+
+        event = dict(log_format="XYZZY", log_time=12345)
+        self.assertEqual(
+            formatEventAsClassicLogText(event, formatTime=formatTime),
+            "__12345__ [-\x23-] XYZZY\n",
+        )
+
+    def test_formatNamespace(self) -> None:
+        """
+        Namespace is first part of second field.
+        """
+        event = dict(log_format="XYZZY", log_namespace="my.namespace")
+        self.assertEqual(
+            formatEventAsClassicLogText(event),
+            "- [my.namespace\x23-] XYZZY\n",
+        )
+
+    def test_formatLevel(self) -> None:
+        """
+        Level is second part of second field.
+        """
+        event = dict(log_format="XYZZY", log_level=LogLevel.warn)
+        self.assertEqual(
+            formatEventAsClassicLogText(event),
+            "- [-\x23warn] XYZZY\n",
+        )
+
+    def test_formatSystem(self) -> None:
+        """
+        System is second field.
+        """
+        event = dict(log_format="XYZZY", log_system="S.Y.S.T.E.M.")
+        self.assertEqual(
+            formatEventAsClassicLogText(event),
+            "- [S.Y.S.T.E.M.] XYZZY\n",
+        )
+
+    def test_formatSystemRulz(self) -> None:
+        """
+        System is not supplanted by namespace and level.
+        """
+        event = dict(
+            log_format="XYZZY",
+            log_namespace="my.namespace",
+            log_level=LogLevel.warn,
+            log_system="S.Y.S.T.E.M.",
+        )
+        self.assertEqual(
+            formatEventAsClassicLogText(event),
+            "- [S.Y.S.T.E.M.] XYZZY\n",
+        )
+
+    def test_formatSystemUnformattable(self) -> None:
+        """
+        System is not supplanted by namespace and level.
+        """
+        event = dict(log_format="XYZZY", log_system=Unformattable())
+        self.assertEqual(
+            formatEventAsClassicLogText(event),
+            "- [UNFORMATTABLE] XYZZY\n",
+        )
+
+    def test_formatFormat(self) -> None:
+        """
+        Formatted event is last field.
+        """
+        event = dict(log_format="id:{id}", id="123")
+        self.assertEqual(
+            formatEventAsClassicLogText(event),
+            "- [-\x23-] id:123\n",
+        )
+
+    def test_formatNoFormat(self) -> None:
+        """
+        No format string.
+        """
+        event = dict(id="123")
+        self.assertIs(formatEventAsClassicLogText(event), None)
+
+    def test_formatEmptyFormat(self) -> None:
+        """
+        Empty format string.
+        """
+        event = dict(log_format="", id="123")
+        self.assertIs(formatEventAsClassicLogText(event), None)
+
+    def test_formatFormatMultiLine(self) -> None:
+        """
+        If the formatted event has newlines, indent additional lines.
+        """
+        event = dict(log_format='XYZZY\nA hollow voice says:\n"Plugh"')
+        self.assertEqual(
+            formatEventAsClassicLogText(event),
+            '- [-\x23-] XYZZY\n\tA hollow voice says:\n\t"Plugh"\n',
+        )
+
+
+class FormatFieldTests(unittest.TestCase):
+    """
+    Tests for format field functions.
+    """
+
+    def test_formatWithCall(self) -> None:
+        """
+        L{formatWithCall} is an extended version of L{str.format} that
+        will interpret a set of parentheses "C{()}" at the end of a format key
+        to mean that the format key ought to be I{called} rather than
+        stringified.
+        """
+        self.assertEqual(
+            formatWithCall(
+                "Hello, {world}. {callme()}.",
+                dict(world="earth", callme=lambda: "maybe"),
+            ),
+            "Hello, earth. maybe.",
+        )
+        self.assertEqual(
+            formatWithCall("Hello, {repr()!r}.", dict(repr=lambda: "repr")),
+            "Hello, 'repr'.",
+        )
+
+
+class Unformattable:
+    """
+    An object that raises an exception from C{__repr__}.
+    """
+
+    def __repr__(self) -> str:
+        return str(1 / 0)
+
+
+class CapturedError(Exception):
+    """
+    A captured error for use in format tests.
+    """
+
+
+class EventAsTextTests(unittest.TestCase):
+    """
+    Tests for L{eventAsText}, all of which ensure that the
+    returned type is UTF-8 decoded text.
+    """
+
+    def test_eventWithTraceback(self) -> None:
+        """
+        An event with a C{log_failure} key will have a traceback appended.
+        """
+        try:
+            raise CapturedError("This is a fake error")
+        except CapturedError:
+            f = Failure()
+
+        event: LogEvent = {"log_format": "This is a test log message"}
+        event["log_failure"] = f
+        eventText = eventAsText(event, includeTimestamp=True, includeSystem=False)
+        self.assertIn(str(f.getTraceback()), eventText)
+        self.assertIn("This is a test log message", eventText)
+
+    def test_formatEmptyEventWithTraceback(self) -> None:
+        """
+        An event with an empty C{log_format} key appends a traceback from
+        the accompanying failure.
+        """
+        try:
+            raise CapturedError("This is a fake error")
+        except CapturedError:
+            f = Failure()
+        event: LogEvent = {"log_format": ""}
+        event["log_failure"] = f
+        eventText = eventAsText(event, includeTimestamp=True, includeSystem=False)
+        self.assertIn(str(f.getTraceback()), eventText)
+        self.assertIn("This is a fake error", eventText)
+
+    def test_formatUnformattableWithTraceback(self) -> None:
+        """
+        An event with an unformattable value in the C{log_format} key still
+        has a traceback appended.
+        """
+        try:
+            raise CapturedError("This is a fake error")
+        except CapturedError:
+            f = Failure()
+
+        event = {
+            "log_format": "{evil()}",
+            "evil": lambda: 1 / 0,
+        }
+        event["log_failure"] = f
+        eventText = eventAsText(event, includeTimestamp=True, includeSystem=False)
+        self.assertIsInstance(eventText, str)
+        self.assertIn(str(f.getTraceback()), eventText)
+        self.assertIn("This is a fake error", eventText)
+
+    def test_formatUnformattableErrorWithTraceback(self) -> None:
+        """
+        An event with an unformattable value in the C{log_format} key, that
+        throws an exception when __repr__ is invoked still has a traceback
+        appended.
+        """
+        try:
+            raise CapturedError("This is a fake error")
+        except CapturedError:
+            f = Failure()
+
+        event: LogEvent = {
+            "log_format": "{evil()}",
+            "evil": lambda: 1 / 0,
+            cast(str, Unformattable()): "gurk",
+        }
+        event["log_failure"] = f
+        eventText = eventAsText(event, includeTimestamp=True, includeSystem=False)
+        self.assertIsInstance(eventText, str)
+        self.assertIn("MESSAGE LOST", eventText)
+        self.assertIn(str(f.getTraceback()), eventText)
+        self.assertIn("This is a fake error", eventText)
+
+    def test_formatEventUnformattableTraceback(self) -> None:
+        """
+        If a traceback cannot be appended, a message indicating this is true
+        is appended.
+        """
+        event: LogEvent = {"log_format": ""}
+        event["log_failure"] = object()
+        eventText = eventAsText(event, includeTimestamp=True, includeSystem=False)
+        self.assertIsInstance(eventText, str)
+        self.assertIn("(UNABLE TO OBTAIN TRACEBACK FROM EVENT)", eventText)
+
+    def test_formatEventNonCritical(self) -> None:
+        """
+        An event with no C{log_failure} key will not have a traceback appended.
+        """
+        event: LogEvent = {"log_format": "This is a test log message"}
+        eventText = eventAsText(event, includeTimestamp=True, includeSystem=False)
+        self.assertIsInstance(eventText, str)
+        self.assertIn("This is a test log message", eventText)
+
+    def test_formatTracebackMultibyte(self) -> None:
+        """
+        An exception message with multibyte characters is properly handled.
+        """
+        try:
+            raise CapturedError("€")
+        except CapturedError:
+            f = Failure()
+
+        event: LogEvent = {"log_format": "This is a test log message"}
+        event["log_failure"] = f
+        eventText = eventAsText(event, includeTimestamp=True, includeSystem=False)
+        self.assertIn("€", eventText)
+        self.assertIn("Traceback", eventText)
+
+    def test_formatTracebackHandlesUTF8DecodeFailure(self) -> None:
+        """
+        An error raised attempting to decode the UTF still produces a
+        valid log message.
+        """
+        try:
+            # 'test' in utf-16
+            raise CapturedError(b"\xff\xfet\x00e\x00s\x00t\x00")
+        except CapturedError:
+            f = Failure()
+
+        event: LogEvent = {"log_format": "This is a test log message"}
+        event["log_failure"] = f
+        eventText = eventAsText(event, includeTimestamp=True, includeSystem=False)
+        self.assertIn("Traceback", eventText)
+        self.assertIn(r'CapturedError(b"\xff\xfet\x00e\x00s\x00t\x00")', eventText)
+
+    def test_eventAsTextSystemOnly(self) -> None:
+        """
+        If includeSystem is specified as the only option no timestamp or
+        traceback are printed.
+        """
+        try:
+            raise CapturedError("This is a fake error")
+        except CapturedError:
+            f = Failure()
+
+        t = mktime((2013, 9, 24, 11, 40, 47, 1, 267, -1))
+        event: LogEvent = {
+            "log_format": "ABCD",
+            "log_system": "fake_system",
+            "log_time": t,
+        }
+        event["log_failure"] = f
+        eventText = eventAsText(
+            event,
+            includeTimestamp=False,
+            includeTraceback=False,
+            includeSystem=True,
+        )
+        self.assertEqual(
+            eventText,
+            "[fake_system] ABCD",
+        )
+
+    def test_eventAsTextTimestampOnly(self) -> None:
+        """
+        If includeTimestamp is specified as the only option no system or
+        traceback are printed.
+        """
+        if tzset is None:
+            raise SkipTest("Platform cannot change timezone; unable to verify offsets.")
+
+        addTZCleanup(self)
+        setTZ("UTC+00")
+
+        try:
+            raise CapturedError("This is a fake error")
+        except CapturedError:
+            f = Failure()
+
+        t = mktime((2013, 9, 24, 11, 40, 47, 1, 267, -1))
+        event: LogEvent = {
+            "log_format": "ABCD",
+            "log_system": "fake_system",
+            "log_time": t,
+        }
+        event["log_failure"] = f
+        eventText = eventAsText(
+            event,
+            includeTimestamp=True,
+            includeTraceback=False,
+            includeSystem=False,
+        )
+        self.assertEqual(
+            eventText,
+            "2013-09-24T11:40:47+0000 ABCD",
+        )
+
+    def test_eventAsTextSystemMissing(self) -> None:
+        """
+        If includeSystem is specified with a missing system [-#-]
+        is used.
+        """
+        try:
+            raise CapturedError("This is a fake error")
+        except CapturedError:
+            f = Failure()
+
+        t = mktime((2013, 9, 24, 11, 40, 47, 1, 267, -1))
+        event: LogEvent = {
+            "log_format": "ABCD",
+            "log_time": t,
+        }
+        event["log_failure"] = f
+        eventText = eventAsText(
+            event,
+            includeTimestamp=False,
+            includeTraceback=False,
+            includeSystem=True,
+        )
+        self.assertEqual(
+            eventText,
+            "[-\x23-] ABCD",
+        )
+
+    def test_eventAsTextSystemMissingNamespaceAndLevel(self) -> None:
+        """
+        If includeSystem is specified with a missing system but
+        namespace and level are present they are used.
+        """
+        try:
+            raise CapturedError("This is a fake error")
+        except CapturedError:
+            f = Failure()
+
+        t = mktime((2013, 9, 24, 11, 40, 47, 1, 267, -1))
+        event: LogEvent = {
+            "log_format": "ABCD",
+            "log_time": t,
+            "log_level": LogLevel.info,
+            "log_namespace": "test",
+        }
+        event["log_failure"] = f
+        eventText = eventAsText(
+            event,
+            includeTimestamp=False,
+            includeTraceback=False,
+            includeSystem=True,
+        )
+        self.assertEqual(
+            eventText,
+            "[test\x23info] ABCD",
+        )
+
+    def test_eventAsTextSystemMissingLevelOnly(self) -> None:
+        """
+        If includeSystem is specified with a missing system but
+        level is present, level is included.
+        """
+        try:
+            raise CapturedError("This is a fake error")
+        except CapturedError:
+            f = Failure()
+
+        t = mktime((2013, 9, 24, 11, 40, 47, 1, 267, -1))
+        event: LogEvent = {
+            "log_format": "ABCD",
+            "log_time": t,
+            "log_level": LogLevel.info,
+        }
+        event["log_failure"] = f
+        eventText = eventAsText(
+            event,
+            includeTimestamp=False,
+            includeTraceback=False,
+            includeSystem=True,
+        )
+        self.assertEqual(
+            eventText,
+            "[-\x23info] ABCD",
+        )
+
+    def test_eventAsTextTypeAsInput(self) -> None:
+        """
+        C{eventAsText} can handle formats that have classes or types as input.
+        """
+
+        def getText(logFormat: str, **event: Any) -> str:
+            return eventAsText(
+                {"log_format": logFormat, **event},
+                includeTimestamp=False,
+                includeTraceback=False,
+                includeSystem=False,
+            )
+
+        self.assertEqual(str(int), getText("{c}", c=int))
+        self.assertEqual(str(RuntimeError), getText("{c}", c=RuntimeError))
+        self.assertEqual("str", getText("{c.__name__}", c=str))

backend/lib/python3.12/site-packages/twisted/logger/test/test_global.py

@@ -0,0 +1,352 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._global}.
+"""
+
+import io
+from typing import IO, Any, List, Optional, TextIO, Tuple, Type, cast
+
+from twisted.python.failure import Failure
+from twisted.trial import unittest
+from .._file import textFileLogObserver
+from .._global import MORE_THAN_ONCE_WARNING, LogBeginner
+from .._interfaces import ILogObserver, LogEvent
+from .._levels import LogLevel
+from .._logger import Logger
+from .._observer import LogPublisher
+from ..test.test_stdlib import nextLine
+
+
+def compareEvents(
+    test: unittest.TestCase,
+    actualEvents: List[LogEvent],
+    expectedEvents: List[LogEvent],
+) -> None:
+    """
+    Compare two sequences of log events, examining only the the keys which are
+    present in both.
+
+    @param test: a test case doing the comparison
+    @param actualEvents: A list of log events that were emitted by a logger.
+    @param expectedEvents: A list of log events that were expected by a test.
+    """
+    if len(actualEvents) != len(expectedEvents):
+        test.assertEqual(actualEvents, expectedEvents)
+    allMergedKeys = set()
+
+    for event in expectedEvents:
+        allMergedKeys |= set(event.keys())
+
+    def simplify(event: LogEvent) -> LogEvent:
+        copy = event.copy()
+        for key in event.keys():
+            if key not in allMergedKeys:
+                copy.pop(key)
+        return copy
+
+    simplifiedActual = [simplify(event) for event in actualEvents]
+    test.assertEqual(simplifiedActual, expectedEvents)
+
+
+class LogBeginnerTests(unittest.TestCase):
+    """
+    Tests for L{LogBeginner}.
+    """
+
+    def setUp(self) -> None:
+        self.publisher = LogPublisher()
+        self.errorStream = io.StringIO()
+
+        class NotSys:
+            stdout = object()
+            stderr = object()
+
+        class NotWarnings:
+            def __init__(self) -> None:
+                self.warnings: List[
+                    Tuple[
+                        str, Type[Warning], str, int, Optional[IO[Any]], Optional[int]
+                    ]
+                ] = []
+
+            def showwarning(
+                self,
+                message: str,
+                category: Type[Warning],
+                filename: str,
+                lineno: int,
+                file: Optional[IO[Any]] = None,
+                line: Optional[int] = None,
+            ) -> None:
+                """
+                Emulate warnings.showwarning.
+
+                @param message: A warning message to emit.
+                @param category: A warning category to associate with
+                    C{message}.
+                @param filename: A file name for the source code file issuing
+                    the warning.
+                @param lineno: A line number in the source file where the
+                    warning was issued.
+                @param file: A file to write the warning message to.  If
+                    L{None}, write to L{sys.stderr}.
+                @param line: A line of source code to include with the warning
+                    message. If L{None}, attempt to read the line from
+                    C{filename} and C{lineno}.
+                """
+                self.warnings.append((message, category, filename, lineno, file, line))
+
+        self.sysModule = NotSys()
+        self.warningsModule = NotWarnings()
+        self.beginner = LogBeginner(
+            self.publisher, self.errorStream, self.sysModule, self.warningsModule
+        )
+
+    def test_beginLoggingToAddObservers(self) -> None:
+        """
+        Test that C{beginLoggingTo()} adds observers.
+        """
+        event = dict(foo=1, bar=2)
+
+        events1: List[LogEvent] = []
+        events2: List[LogEvent] = []
+
+        o1 = cast(ILogObserver, lambda e: events1.append(e))
+        o2 = cast(ILogObserver, lambda e: events2.append(e))
+
+        self.beginner.beginLoggingTo((o1, o2))
+        self.publisher(event)
+
+        self.assertEqual([event], events1)
+        self.assertEqual([event], events2)
+
+    def test_beginLoggingToBufferedEvents(self) -> None:
+        """
+        Test that events are buffered until C{beginLoggingTo()} is
+        called.
+        """
+        event = dict(foo=1, bar=2)
+
+        events1: List[LogEvent] = []
+        events2: List[LogEvent] = []
+
+        o1 = cast(ILogObserver, lambda e: events1.append(e))
+        o2 = cast(ILogObserver, lambda e: events2.append(e))
+
+        self.publisher(event)  # Before beginLoggingTo; this is buffered
+        self.beginner.beginLoggingTo((o1, o2))
+
+        self.assertEqual([event], events1)
+        self.assertEqual([event], events2)
+
+    def _bufferLimitTest(self, limit: int, beginner: LogBeginner) -> None:
+        """
+        Verify that when more than C{limit} events are logged to L{LogBeginner},
+        only the last C{limit} are replayed by L{LogBeginner.beginLoggingTo}.
+
+        @param limit: The maximum number of events the log beginner should
+            buffer.
+        @param beginner: The L{LogBeginner} against which to verify.
+
+        @raise: C{self.failureException} if the wrong events are replayed by
+            C{beginner}.
+        """
+        for count in range(limit + 1):
+            self.publisher(dict(count=count))
+        events: List[LogEvent] = []
+        beginner.beginLoggingTo([cast(ILogObserver, events.append)])
+        self.assertEqual(
+            list(range(1, limit + 1)),
+            list(event["count"] for event in events),
+        )
+
+    def test_defaultBufferLimit(self) -> None:
+        """
+        Up to C{LogBeginner._DEFAULT_BUFFER_SIZE} log events are buffered for
+        replay by L{LogBeginner.beginLoggingTo}.
+        """
+        limit = LogBeginner._DEFAULT_BUFFER_SIZE
+        self._bufferLimitTest(limit, self.beginner)
+
+    def test_overrideBufferLimit(self) -> None:
+        """
+        The size of the L{LogBeginner} event buffer can be overridden with the
+        C{initialBufferSize} initilizer argument.
+        """
+        limit = 3
+        beginner = LogBeginner(
+            self.publisher,
+            self.errorStream,
+            self.sysModule,
+            self.warningsModule,
+            initialBufferSize=limit,
+        )
+        self._bufferLimitTest(limit, beginner)
+
+    def test_beginLoggingToTwice(self) -> None:
+        """
+        When invoked twice, L{LogBeginner.beginLoggingTo} will emit a log
+        message warning the user that they previously began logging, and add
+        the new log observers.
+        """
+        events1: List[LogEvent] = []
+        events2: List[LogEvent] = []
+        fileHandle = io.StringIO()
+        textObserver = textFileLogObserver(fileHandle)
+        self.publisher(dict(event="prebuffer"))
+        firstFilename, firstLine = nextLine()
+        self.beginner.beginLoggingTo([cast(ILogObserver, events1.append), textObserver])
+        self.publisher(dict(event="postbuffer"))
+        secondFilename, secondLine = nextLine()
+        self.beginner.beginLoggingTo([cast(ILogObserver, events2.append), textObserver])
+        self.publisher(dict(event="postwarn"))
+        warning = dict(
+            log_format=MORE_THAN_ONCE_WARNING,
+            log_level=LogLevel.warn,
+            fileNow=secondFilename,
+            lineNow=secondLine,
+            fileThen=firstFilename,
+            lineThen=firstLine,
+        )
+
+        self.maxDiff = None
+        compareEvents(
+            self,
+            events1,
+            [
+                dict(event="prebuffer"),
+                dict(event="postbuffer"),
+                warning,
+                dict(event="postwarn"),
+            ],
+        )
+        compareEvents(self, events2, [warning, dict(event="postwarn")])
+
+        output = fileHandle.getvalue()
+        self.assertIn(f"<{firstFilename}:{firstLine}>", output)
+        self.assertIn(f"<{secondFilename}:{secondLine}>", output)
+
+    def test_criticalLogging(self) -> None:
+        """
+        Critical messages will be written as text to the error stream.
+        """
+        log = Logger(observer=self.publisher)
+        log.info("ignore this")
+        log.critical("a critical {message}", message="message")
+        self.assertEqual(self.errorStream.getvalue(), "a critical message\n")
+
+    def test_criticalLoggingStops(self) -> None:
+        """
+        Once logging has begun with C{beginLoggingTo}, critical messages are no
+        longer written to the output stream.
+        """
+        log = Logger(observer=self.publisher)
+        self.beginner.beginLoggingTo(())
+        log.critical("another critical message")
+        self.assertEqual(self.errorStream.getvalue(), "")
+
+    def test_beginLoggingToRedirectStandardIO(self) -> None:
+        """
+        L{LogBeginner.beginLoggingTo} will re-direct the standard output and
+        error streams by setting the C{stdio} and C{stderr} attributes on its
+        sys module object.
+        """
+        events: List[LogEvent] = []
+        self.beginner.beginLoggingTo([cast(ILogObserver, events.append)])
+        print("Hello, world.", file=cast(TextIO, self.sysModule.stdout))
+        compareEvents(
+            self, events, [dict(log_namespace="stdout", log_io="Hello, world.")]
+        )
+        del events[:]
+        print("Error, world.", file=cast(TextIO, self.sysModule.stderr))
+        compareEvents(
+            self, events, [dict(log_namespace="stderr", log_io="Error, world.")]
+        )
+
+    def test_beginLoggingToDontRedirect(self) -> None:
+        """
+        L{LogBeginner.beginLoggingTo} will leave the existing stdout/stderr in
+        place if it has been told not to replace them.
+        """
+        oldOut = self.sysModule.stdout
+        oldErr = self.sysModule.stderr
+        self.beginner.beginLoggingTo((), redirectStandardIO=False)
+        self.assertIs(self.sysModule.stdout, oldOut)
+        self.assertIs(self.sysModule.stderr, oldErr)
+
+    def test_beginLoggingToPreservesEncoding(self) -> None:
+        """
+        When L{LogBeginner.beginLoggingTo} redirects stdout/stderr streams, the
+        replacement streams will preserve the encoding of the replaced streams,
+        to minimally disrupt any application relying on a specific encoding.
+        """
+
+        weird = io.TextIOWrapper(io.BytesIO(), "shift-JIS")
+        weirderr = io.TextIOWrapper(io.BytesIO(), "big5")
+
+        self.sysModule.stdout = weird
+        self.sysModule.stderr = weirderr
+
+        events: List[LogEvent] = []
+        self.beginner.beginLoggingTo([cast(ILogObserver, events.append)])
+        stdout = cast(TextIO, self.sysModule.stdout)
+        stderr = cast(TextIO, self.sysModule.stderr)
+        self.assertEqual(stdout.encoding, "shift-JIS")
+        self.assertEqual(stderr.encoding, "big5")
+
+        stdout.write(b"\x97\x9B\n")  # type: ignore[call-overload]
+        stderr.write(b"\xBC\xFC\n")  # type: ignore[call-overload]
+        compareEvents(self, events, [dict(log_io="\u674e"), dict(log_io="\u7469")])
+
+    def test_warningsModule(self) -> None:
+        """
+        L{LogBeginner.beginLoggingTo} will redirect the warnings of its
+        warnings module into the logging system.
+        """
+        self.warningsModule.showwarning("a message", DeprecationWarning, __file__, 1)
+        events: List[LogEvent] = []
+        self.beginner.beginLoggingTo([cast(ILogObserver, events.append)])
+        self.warningsModule.showwarning(
+            "another message", DeprecationWarning, __file__, 2
+        )
+        f = io.StringIO()
+        self.warningsModule.showwarning(
+            "yet another", DeprecationWarning, __file__, 3, file=f
+        )
+        self.assertEqual(
+            self.warningsModule.warnings,
+            [
+                ("a message", DeprecationWarning, __file__, 1, None, None),
+                ("yet another", DeprecationWarning, __file__, 3, f, None),
+            ],
+        )
+        compareEvents(
+            self,
+            events,
+            [
+                dict(
+                    warning="another message",
+                    category=(
+                        DeprecationWarning.__module__
+                        + "."
+                        + DeprecationWarning.__name__
+                    ),
+                    filename=__file__,
+                    lineno=2,
+                )
+            ],
+        )
+
+    def test_failuresAppendTracebacks(self) -> None:
+        """
+        The string resulting from a logged failure contains a traceback.
+        """
+        f = Failure(Exception("this is not the behavior you are looking for"))
+        log = Logger(observer=self.publisher)
+        log.failure("a failure", failure=f)
+        msg = self.errorStream.getvalue()
+        self.assertIn("a failure", msg)
+        self.assertIn("this is not the behavior you are looking for", msg)
+        self.assertIn("Traceback", msg)

backend/lib/python3.12/site-packages/twisted/logger/test/test_io.py

@@ -0,0 +1,289 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._io}.
+"""
+
+import sys
+from typing import List, Optional
+
+from zope.interface import implementer
+
+from constantly import NamedConstant
+
+from twisted.trial import unittest
+from .._interfaces import ILogObserver, LogEvent
+from .._io import LoggingFile
+from .._levels import LogLevel
+from .._logger import Logger
+from .._observer import LogPublisher
+
+
+@implementer(ILogObserver)
+class TestLoggingFile(LoggingFile):
+    """
+    L{LoggingFile} that is also an observer which captures events and messages.
+    """
+
+    def __init__(
+        self,
+        logger: Logger,
+        level: NamedConstant = LogLevel.info,
+        encoding: Optional[str] = None,
+    ) -> None:
+        super().__init__(logger=logger, level=level, encoding=encoding)
+        self.events: List[LogEvent] = []
+        self.messages: List[str] = []
+
+    def __call__(self, event: LogEvent) -> None:
+        self.events.append(event)
+        if "log_io" in event:
+            self.messages.append(event["log_io"])
+
+
+class LoggingFileTests(unittest.TestCase):
+    """
+    Tests for L{LoggingFile}.
+    """
+
+    def setUp(self) -> None:
+        """
+        Create a logger for test L{LoggingFile} instances to use.
+        """
+        self.publisher = LogPublisher()
+        self.logger = Logger(observer=self.publisher)
+
+    def test_softspace(self) -> None:
+        """
+        L{LoggingFile.softspace} is 0.
+        """
+        self.assertEqual(LoggingFile(self.logger).softspace, 0)
+
+        warningsShown = self.flushWarnings([self.test_softspace])
+        self.assertEqual(len(warningsShown), 1)
+        self.assertEqual(warningsShown[0]["category"], DeprecationWarning)
+        deprecatedClass = "twisted.logger._io.LoggingFile.softspace"
+        self.assertEqual(
+            warningsShown[0]["message"],
+            "%s was deprecated in Twisted 21.2.0" % (deprecatedClass),
+        )
+
+    def test_readOnlyAttributes(self) -> None:
+        """
+        Some L{LoggingFile} attributes are read-only.
+        """
+        f = LoggingFile(self.logger)
+
+        self.assertRaises(AttributeError, setattr, f, "closed", True)
+        self.assertRaises(AttributeError, setattr, f, "encoding", "utf-8")
+        self.assertRaises(AttributeError, setattr, f, "mode", "r")
+        self.assertRaises(AttributeError, setattr, f, "newlines", ["\n"])
+        self.assertRaises(AttributeError, setattr, f, "name", "foo")
+
+    def test_unsupportedMethods(self) -> None:
+        """
+        Some L{LoggingFile} methods are unsupported.
+        """
+        f = LoggingFile(self.logger)
+
+        self.assertRaises(IOError, f.read)
+        self.assertRaises(IOError, f.next)
+        self.assertRaises(IOError, f.readline)
+        self.assertRaises(IOError, f.readlines)
+        self.assertRaises(IOError, f.xreadlines)
+        self.assertRaises(IOError, f.seek)
+        self.assertRaises(IOError, f.tell)
+        self.assertRaises(IOError, f.truncate)
+
+    def test_level(self) -> None:
+        """
+        Default level is L{LogLevel.info} if not set.
+        """
+        f = LoggingFile(self.logger)
+        self.assertEqual(f.level, LogLevel.info)
+
+        f = LoggingFile(self.logger, level=LogLevel.error)
+        self.assertEqual(f.level, LogLevel.error)
+
+    def test_encoding(self) -> None:
+        """
+        Default encoding is C{sys.getdefaultencoding()} if not set.
+        """
+        f = LoggingFile(self.logger)
+        self.assertEqual(f.encoding, sys.getdefaultencoding())
+
+        f = LoggingFile(self.logger, encoding="utf-8")
+        self.assertEqual(f.encoding, "utf-8")
+
+    def test_mode(self) -> None:
+        """
+        Reported mode is C{"w"}.
+        """
+        f = LoggingFile(self.logger)
+        self.assertEqual(f.mode, "w")
+
+    def test_newlines(self) -> None:
+        """
+        The C{newlines} attribute is L{None}.
+        """
+        f = LoggingFile(self.logger)
+        self.assertIsNone(f.newlines)
+
+    def test_name(self) -> None:
+        """
+        The C{name} attribute is fixed.
+        """
+        f = LoggingFile(self.logger)
+        self.assertEqual(f.name, "<LoggingFile twisted.logger.test.test_io#info>")
+
+    def test_close(self) -> None:
+        """
+        L{LoggingFile.close} closes the file.
+        """
+        f = LoggingFile(self.logger)
+        f.close()
+
+        self.assertTrue(f.closed)
+        self.assertRaises(ValueError, f.write, "Hello")
+
+    def test_flush(self) -> None:
+        """
+        L{LoggingFile.flush} does nothing.
+        """
+        f = LoggingFile(self.logger)
+        f.flush()
+
+    def test_fileno(self) -> None:
+        """
+        L{LoggingFile.fileno} returns C{-1}.
+        """
+        f = LoggingFile(self.logger)
+        self.assertEqual(f.fileno(), -1)
+
+    def test_isatty(self) -> None:
+        """
+        L{LoggingFile.isatty} returns C{False}.
+        """
+        f = LoggingFile(self.logger)
+        self.assertFalse(f.isatty())
+
+    def test_writeBuffering(self) -> None:
+        """
+        Writing buffers correctly.
+        """
+        f = self.observedFile()
+        f.write("Hello")
+        self.assertEqual(f.messages, [])
+        f.write(", world!\n")
+        self.assertEqual(f.messages, ["Hello, world!"])
+        f.write("It's nice to meet you.\n\nIndeed.")
+        self.assertEqual(
+            f.messages,
+            [
+                "Hello, world!",
+                "It's nice to meet you.",
+                "",
+            ],
+        )
+
+    def test_writeBytesDecoded(self) -> None:
+        """
+        Bytes are decoded to text.
+        """
+        f = self.observedFile(encoding="utf-8")
+        f.write(b"Hello, Mr. S\xc3\xa1nchez\n")
+        self.assertEqual(f.messages, ["Hello, Mr. S\xe1nchez"])
+
+    def test_writeUnicode(self) -> None:
+        """
+        Unicode is unmodified.
+        """
+        f = self.observedFile(encoding="utf-8")
+        f.write("Hello, Mr. S\xe1nchez\n")
+        self.assertEqual(f.messages, ["Hello, Mr. S\xe1nchez"])
+
+    def test_writeLevel(self) -> None:
+        """
+        Log level is emitted properly.
+        """
+        f = self.observedFile()
+        f.write("Hello\n")
+        self.assertEqual(len(f.events), 1)
+        self.assertEqual(f.events[0]["log_level"], LogLevel.info)
+
+        f = self.observedFile(level=LogLevel.error)
+        f.write("Hello\n")
+        self.assertEqual(len(f.events), 1)
+        self.assertEqual(f.events[0]["log_level"], LogLevel.error)
+
+    def test_writeFormat(self) -> None:
+        """
+        Log format is C{"{message}"}.
+        """
+        f = self.observedFile()
+        f.write("Hello\n")
+        self.assertEqual(len(f.events), 1)
+        self.assertEqual(f.events[0]["log_format"], "{log_io}")
+
+    def test_writelinesBuffering(self) -> None:
+        """
+        C{writelines} does not add newlines.
+        """
+        # Note this is different behavior than t.p.log.StdioOnnaStick.
+        f = self.observedFile()
+        f.writelines(("Hello", ", ", ""))
+        self.assertEqual(f.messages, [])
+        f.writelines(("world!\n",))
+        self.assertEqual(f.messages, ["Hello, world!"])
+        f.writelines(("It's nice to meet you.\n\n", "Indeed."))
+        self.assertEqual(
+            f.messages,
+            [
+                "Hello, world!",
+                "It's nice to meet you.",
+                "",
+            ],
+        )
+
+    def test_print(self) -> None:
+        """
+        L{LoggingFile} can replace L{sys.stdout}.
+        """
+        f = self.observedFile()
+        self.patch(sys, "stdout", f)
+
+        print("Hello,", end=" ")
+        print("world.")
+
+        self.assertEqual(f.messages, ["Hello, world."])
+
+    def observedFile(
+        self,
+        level: NamedConstant = LogLevel.info,
+        encoding: Optional[str] = None,
+    ) -> TestLoggingFile:
+        """
+        Construct a L{LoggingFile} with a built-in observer.
+
+        @param level: C{level} argument to L{LoggingFile}
+        @param encoding: C{encoding} argument to L{LoggingFile}
+
+        @return: a L{TestLoggingFile} with an observer that appends received
+            events into the file's C{events} attribute (a L{list}) and
+            event messages into the file's C{messages} attribute (a L{list}).
+        """
+        # Logger takes an observer argument, for which we want to use the
+        # TestLoggingFile we will create, but that takes the Logger as an
+        # argument, so we'll use an array to indirectly reference the
+        # TestLoggingFile.
+        loggingFiles: List[TestLoggingFile] = []
+
+        @implementer(ILogObserver)
+        def observer(event: LogEvent) -> None:
+            loggingFiles[0](event)
+
+        log = Logger(observer=observer)
+        loggingFiles.append(TestLoggingFile(logger=log, level=level, encoding=encoding))
+
+        return loggingFiles[0]

backend/lib/python3.12/site-packages/twisted/logger/test/test_json.py

@@ -0,0 +1,485 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Tests for L{twisted.logger._json}.
+"""
+
+from io import BytesIO, StringIO
+from typing import IO, Any, List, Optional, Sequence, cast
+
+from zope.interface import implementer
+from zope.interface.exceptions import BrokenMethodImplementation
+from zope.interface.verify import verifyObject
+
+from twisted.python.failure import Failure
+from twisted.trial.unittest import TestCase
+from .._flatten import extractField
+from .._format import formatEvent
+from .._global import globalLogPublisher
+from .._interfaces import ILogObserver, LogEvent
+from .._json import (
+    eventAsJSON,
+    eventFromJSON,
+    eventsFromJSONLogFile,
+    jsonFileLogObserver,
+    log as jsonLog,
+)
+from .._levels import LogLevel
+from .._logger import Logger
+from .._observer import LogPublisher
+
+
+def savedJSONInvariants(testCase: TestCase, savedJSON: str) -> str:
+    """
+    Assert a few things about the result of L{eventAsJSON}, then return it.
+
+    @param testCase: The L{TestCase} with which to perform the assertions.
+    @param savedJSON: The result of L{eventAsJSON}.
+
+    @return: C{savedJSON}
+
+    @raise AssertionError: If any of the preconditions fail.
+    """
+    testCase.assertIsInstance(savedJSON, str)
+    testCase.assertEqual(savedJSON.count("\n"), 0)
+    return savedJSON
+
+
+class SaveLoadTests(TestCase):
+    """
+    Tests for loading and saving log events.
+    """
+
+    def savedEventJSON(self, event: LogEvent) -> str:
+        """
+        Serialize some an events, assert some things about it, and return the
+        JSON.
+
+        @param event: An event.
+
+        @return: JSON.
+        """
+        return savedJSONInvariants(self, eventAsJSON(event))
+
+    def test_simpleSaveLoad(self) -> None:
+        """
+        Saving and loading an empty dictionary results in an empty dictionary.
+        """
+        self.assertEqual(eventFromJSON(self.savedEventJSON({})), {})
+
+    def test_saveLoad(self) -> None:
+        """
+        Saving and loading a dictionary with some simple values in it results
+        in those same simple values in the output; according to JSON's rules,
+        though, all dictionary keys must be L{str} and any non-L{str}
+        keys will be converted.
+        """
+        self.assertEqual(
+            eventFromJSON(self.savedEventJSON({1: 2, "3": "4"})),  # type: ignore[dict-item]
+            {"1": 2, "3": "4"},
+        )
+
+    def test_saveUnPersistable(self) -> None:
+        """
+        Saving and loading an object which cannot be represented in JSON will
+        result in a placeholder.
+        """
+        self.assertEqual(
+            eventFromJSON(self.savedEventJSON({"1": 2, "3": object()})),
+            {"1": 2, "3": {"unpersistable": True}},
+        )
+
+    def test_saveNonASCII(self) -> None:
+        """
+        Non-ASCII keys and values can be saved and loaded.
+        """
+        self.assertEqual(
+            eventFromJSON(self.savedEventJSON({"\u1234": "\u4321", "3": object()})),
+            {"\u1234": "\u4321", "3": {"unpersistable": True}},
+        )
+
+    def test_saveBytes(self) -> None:
+        """
+        Any L{bytes} objects will be saved as if they are latin-1 so they can
+        be faithfully re-loaded.
+        """
+        inputEvent = {"hello": bytes(range(255))}
+        # On Python 3, bytes keys will be skipped by the JSON encoder. Not
+        # much we can do about that.  Let's make sure that we don't get an
+        # error, though.
+        inputEvent.update({b"skipped": "okay"})  # type: ignore[dict-item]
+        self.assertEqual(
+            eventFromJSON(self.savedEventJSON(inputEvent)),
+            {"hello": bytes(range(255)).decode("charmap")},
+        )
+
+    def test_saveUnPersistableThenFormat(self) -> None:
+        """
+        Saving and loading an object which cannot be represented in JSON, but
+        has a string representation which I{can} be saved as JSON, will result
+        in the same string formatting; any extractable fields will retain their
+        data types.
+        """
+
+        class Reprable:
+            def __init__(self, value: object) -> None:
+                self.value = value
+
+            def __repr__(self) -> str:
+                return "reprable"
+
+        inputEvent = {"log_format": "{object} {object.value}", "object": Reprable(7)}
+        outputEvent = eventFromJSON(self.savedEventJSON(inputEvent))
+        self.assertEqual(formatEvent(outputEvent), "reprable 7")
+
+    def test_extractingFieldsPostLoad(self) -> None:
+        """
+        L{extractField} can extract fields from an object that's been saved and
+        loaded from JSON.
+        """
+
+        class Obj:
+            def __init__(self) -> None:
+                self.value = 345
+
+        inputEvent = dict(log_format="{object.value}", object=Obj())
+        loadedEvent = eventFromJSON(self.savedEventJSON(inputEvent))
+        self.assertEqual(extractField("object.value", loadedEvent), 345)
+
+        # The behavior of extractField is consistent between pre-persistence
+        # and post-persistence events, although looking up the key directly
+        # won't be:
+        self.assertRaises(KeyError, extractField, "object", loadedEvent)
+        self.assertRaises(KeyError, extractField, "object", inputEvent)
+
+    def test_failureStructurePreserved(self) -> None:
+        """
+        Round-tripping a failure through L{eventAsJSON} preserves its class and
+        structure.
+        """
+        events: List[LogEvent] = []
+        log = Logger(observer=cast(ILogObserver, events.append))
+        try:
+            1 / 0
+        except ZeroDivisionError:
+            f = Failure()
+            log.failure("a message about failure", f)
+        self.assertEqual(len(events), 1)
+        loaded = eventFromJSON(self.savedEventJSON(events[0]))["log_failure"]
+        self.assertIsInstance(loaded, Failure)
+        self.assertTrue(loaded.check(ZeroDivisionError))
+        self.assertIsInstance(loaded.getTraceback(), str)
+
+    def test_saveLoadLevel(self) -> None:
+        """
+        It's important that the C{log_level} key remain a
+        L{constantly.NamedConstant} object.
+        """
+        inputEvent = dict(log_level=LogLevel.warn)
+        loadedEvent = eventFromJSON(self.savedEventJSON(inputEvent))
+        self.assertIs(loadedEvent["log_level"], LogLevel.warn)
+
+    def test_saveLoadUnknownLevel(self) -> None:
+        """
+        If a saved bit of JSON (let's say, from a future version of Twisted)
+        were to persist a different log_level, it will resolve as None.
+        """
+        loadedEvent = eventFromJSON(
+            '{"log_level": {"name": "other", '
+            '"__class_uuid__": "02E59486-F24D-46AD-8224-3ACDF2A5732A"}}'
+        )
+        self.assertEqual(loadedEvent, dict(log_level=None))
+
+
+class FileLogObserverTests(TestCase):
+    """
+    Tests for L{jsonFileLogObserver}.
+    """
+
+    def test_interface(self) -> None:
+        """
+        A L{FileLogObserver} returned by L{jsonFileLogObserver} is an
+        L{ILogObserver}.
+        """
+        with StringIO() as fileHandle:
+            observer = jsonFileLogObserver(fileHandle)
+            try:
+                verifyObject(ILogObserver, observer)
+            except BrokenMethodImplementation as e:
+                self.fail(e)
+
+    def assertObserverWritesJSON(self, recordSeparator: str = "\x1e") -> None:
+        """
+        Asserts that an observer created by L{jsonFileLogObserver} with the
+        given arguments writes events serialized as JSON text, using the given
+        record separator.
+
+        @param recordSeparator: C{recordSeparator} argument to
+            L{jsonFileLogObserver}
+        """
+        with StringIO() as fileHandle:
+            observer = jsonFileLogObserver(fileHandle, recordSeparator)
+            event = dict(x=1)
+            observer(event)
+            self.assertEqual(fileHandle.getvalue(), f'{recordSeparator}{{"x": 1}}\n')
+
+    def test_observeWritesDefaultRecordSeparator(self) -> None:
+        """
+        A L{FileLogObserver} created by L{jsonFileLogObserver} writes events
+        serialzed as JSON text to a file when it observes events.
+        By default, the record separator is C{"\\x1e"}.
+        """
+        self.assertObserverWritesJSON()
+
+    def test_observeWritesEmptyRecordSeparator(self) -> None:
+        """
+        A L{FileLogObserver} created by L{jsonFileLogObserver} writes events
+        serialzed as JSON text to a file when it observes events.
+        This test sets the record separator to C{""}.
+        """
+        self.assertObserverWritesJSON(recordSeparator="")
+
+    def test_failureFormatting(self) -> None:
+        """
+        A L{FileLogObserver} created by L{jsonFileLogObserver} writes failures
+        serialized as JSON text to a file when it observes events.
+        """
+        io = StringIO()
+        publisher = LogPublisher()
+        logged: List[LogEvent] = []
+        publisher.addObserver(cast(ILogObserver, logged.append))
+        publisher.addObserver(jsonFileLogObserver(io))
+        logger = Logger(observer=publisher)
+        try:
+            1 / 0
+        except BaseException:
+            logger.failure("failed as expected")
+        reader = StringIO(io.getvalue())
+        deserialized = list(eventsFromJSONLogFile(reader))
+
+        def checkEvents(logEvents: Sequence[LogEvent]) -> None:
+            self.assertEqual(len(logEvents), 1)
+            [failureEvent] = logEvents
+            self.assertIn("log_failure", failureEvent)
+            failureObject = failureEvent["log_failure"]
+            self.assertIsInstance(failureObject, Failure)
+            tracebackObject = failureObject.getTracebackObject()
+            self.assertEqual(
+                tracebackObject.tb_frame.f_code.co_filename.rstrip("co"),
+                __file__.rstrip("co"),
+            )
+
+        checkEvents(logged)
+        checkEvents(deserialized)
+
+
+class LogFileReaderTests(TestCase):
+    """
+    Tests for L{eventsFromJSONLogFile}.
+    """
+
+    def setUp(self) -> None:
+        self.errorEvents: List[LogEvent] = []
+
+        @implementer(ILogObserver)
+        def observer(event: LogEvent) -> None:
+            if event["log_namespace"] == jsonLog.namespace and "record" in event:
+                self.errorEvents.append(event)
+
+        self.logObserver = observer
+
+        globalLogPublisher.addObserver(observer)
+
+    def tearDown(self) -> None:
+        globalLogPublisher.removeObserver(self.logObserver)
+
+    def _readEvents(
+        self,
+        inFile: IO[Any],
+        recordSeparator: Optional[str] = None,
+        bufferSize: int = 4096,
+    ) -> None:
+        """
+        Test that L{eventsFromJSONLogFile} reads two pre-defined events from a
+        file: C{{"x": 1}} and C{{"y": 2}}.
+
+        @param inFile: C{inFile} argument to L{eventsFromJSONLogFile}
+        @param recordSeparator: C{recordSeparator} argument to
+            L{eventsFromJSONLogFile}
+        @param bufferSize: C{bufferSize} argument to L{eventsFromJSONLogFile}
+        """
+        events = iter(eventsFromJSONLogFile(inFile, recordSeparator, bufferSize))
+
+        self.assertEqual(next(events), {"x": 1})
+        self.assertEqual(next(events), {"y": 2})
+        self.assertRaises(StopIteration, next, events)  # No more events
+
+    def test_readEventsAutoWithRecordSeparator(self) -> None:
+        """
+        L{eventsFromJSONLogFile} reads events from a file and automatically
+        detects use of C{"\\x1e"} as the record separator.
+        """
+        with StringIO('\x1e{"x": 1}\n' '\x1e{"y": 2}\n') as fileHandle:
+            self._readEvents(fileHandle)
+            self.assertEqual(len(self.errorEvents), 0)
+
+    def test_readEventsAutoEmptyRecordSeparator(self) -> None:
+        """
+        L{eventsFromJSONLogFile} reads events from a file and automatically
+        detects use of C{""} as the record separator.
+        """
+        with StringIO('{"x": 1}\n' '{"y": 2}\n') as fileHandle:
+            self._readEvents(fileHandle)
+            self.assertEqual(len(self.errorEvents), 0)
+
+    def test_readEventsExplicitRecordSeparator(self) -> None:
+        """
+        L{eventsFromJSONLogFile} reads events from a file and is told to use
+        a specific record separator.
+        """
+        # Use "\x08" (backspace)... because that seems weird enough.
+        with StringIO('\x08{"x": 1}\n' '\x08{"y": 2}\n') as fileHandle:
+            self._readEvents(fileHandle, recordSeparator="\x08")
+            self.assertEqual(len(self.errorEvents), 0)
+
+    def test_readEventsPartialBuffer(self) -> None:
+        """
+        L{eventsFromJSONLogFile} handles buffering a partial event.
+        """
+        with StringIO('\x1e{"x": 1}\n' '\x1e{"y": 2}\n') as fileHandle:
+            # Use a buffer size smaller than the event text.
+            self._readEvents(fileHandle, bufferSize=1)
+            self.assertEqual(len(self.errorEvents), 0)
+
+    def test_readTruncated(self) -> None:
+        """
+        If the JSON text for a record is truncated, skip it.
+        """
+        with StringIO('\x1e{"x": 1' '\x1e{"y": 2}\n') as fileHandle:
+            events = iter(eventsFromJSONLogFile(fileHandle))
+
+            self.assertEqual(next(events), {"y": 2})
+            self.assertRaises(StopIteration, next, events)  # No more events
+
+            # We should have logged the lost record
+            self.assertEqual(len(self.errorEvents), 1)
+            self.assertEqual(
+                self.errorEvents[0]["log_format"],
+                "Unable to read truncated JSON record: {record!r}",
+            )
+            self.assertEqual(self.errorEvents[0]["record"], b'{"x": 1')
+
+    def test_readUnicode(self) -> None:
+        """
+        If the file being read from vends L{str}, strings decode from JSON
+        as-is.
+        """
+        # The Euro currency sign is "\u20ac"
+        with StringIO('\x1e{"currency": "\u20ac"}\n') as fileHandle:
+            events = iter(eventsFromJSONLogFile(fileHandle))
+
+            self.assertEqual(next(events), {"currency": "\u20ac"})
+            self.assertRaises(StopIteration, next, events)  # No more events
+            self.assertEqual(len(self.errorEvents), 0)
+
+    def test_readUTF8Bytes(self) -> None:
+        """
+        If the file being read from vends L{bytes}, strings decode from JSON as
+        UTF-8.
+        """
+        # The Euro currency sign is b"\xe2\x82\xac" in UTF-8
+        with BytesIO(b'\x1e{"currency": "\xe2\x82\xac"}\n') as fileHandle:
+            events = iter(eventsFromJSONLogFile(fileHandle))
+
+            # The Euro currency sign is "\u20ac"
+            self.assertEqual(next(events), {"currency": "\u20ac"})
+            self.assertRaises(StopIteration, next, events)  # No more events
+            self.assertEqual(len(self.errorEvents), 0)
+
+    def test_readTruncatedUTF8Bytes(self) -> None:
+        """
+        If the JSON text for a record is truncated in the middle of a two-byte
+        Unicode codepoint, we don't want to see a codec exception and the
+        stream is read properly when the additional data arrives.
+        """
+        # The Euro currency sign is "\u20ac" and encodes in UTF-8 as three
+        # bytes: b"\xe2\x82\xac".
+        with BytesIO(b'\x1e{"x": "\xe2\x82\xac"}\n') as fileHandle:
+            events = iter(eventsFromJSONLogFile(fileHandle, bufferSize=8))
+
+            self.assertEqual(next(events), {"x": "\u20ac"})  # Got text
+            self.assertRaises(StopIteration, next, events)  # No more events
+            self.assertEqual(len(self.errorEvents), 0)
+
+    def test_readInvalidUTF8Bytes(self) -> None:
+        """
+        If the JSON text for a record contains invalid UTF-8 text, ignore that
+        record.
+        """
+        # The string b"\xe2\xac" is bogus
+        with BytesIO(b'\x1e{"x": "\xe2\xac"}\n' b'\x1e{"y": 2}\n') as fileHandle:
+            events = iter(eventsFromJSONLogFile(fileHandle))
+
+            self.assertEqual(next(events), {"y": 2})
+            self.assertRaises(StopIteration, next, events)  # No more events
+
+            # We should have logged the lost record
+            self.assertEqual(len(self.errorEvents), 1)
+            self.assertEqual(
+                self.errorEvents[0]["log_format"],
+                "Unable to decode UTF-8 for JSON record: {record!r}",
+            )
+            self.assertEqual(self.errorEvents[0]["record"], b'{"x": "\xe2\xac"}\n')
+
+    def test_readInvalidJSON(self) -> None:
+        """
+        If the JSON text for a record is invalid, skip it.
+        """
+        with StringIO('\x1e{"x": }\n' '\x1e{"y": 2}\n') as fileHandle:
+            events = iter(eventsFromJSONLogFile(fileHandle))
+
+            self.assertEqual(next(events), {"y": 2})
+            self.assertRaises(StopIteration, next, events)  # No more events
+
+            # We should have logged the lost record
+            self.assertEqual(len(self.errorEvents), 1)
+            self.assertEqual(
+                self.errorEvents[0]["log_format"],
+                "Unable to read JSON record: {record!r}",
+            )
+            self.assertEqual(self.errorEvents[0]["record"], b'{"x": }\n')
+
+    def test_readUnseparated(self) -> None:
+        """
+        Multiple events without a record separator are skipped.
+        """
+        with StringIO('\x1e{"x": 1}\n' '{"y": 2}\n') as fileHandle:
+            events = eventsFromJSONLogFile(fileHandle)
+
+            self.assertRaises(StopIteration, next, events)  # No more events
+
+            # We should have logged the lost record
+            self.assertEqual(len(self.errorEvents), 1)
+            self.assertEqual(
+                self.errorEvents[0]["log_format"],
+                "Unable to read JSON record: {record!r}",
+            )
+            self.assertEqual(self.errorEvents[0]["record"], b'{"x": 1}\n{"y": 2}\n')
+
+    def test_roundTrip(self) -> None:
+        """
+        Data written by a L{FileLogObserver} returned by L{jsonFileLogObserver}
+        and read by L{eventsFromJSONLogFile} is reconstructed properly.
+        """
+        event = dict(x=1)
+
+        with StringIO() as fileHandle:
+            observer = jsonFileLogObserver(fileHandle)
+            observer(event)
+
+            fileHandle.seek(0)
+            events = eventsFromJSONLogFile(fileHandle)
+
+            self.assertEqual(tuple(events), (event,))
+            self.assertEqual(len(self.errorEvents), 0)

backend/lib/python3.12/site-packages/twisted/logger/test/test_legacy.py

@@ -0,0 +1,413 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._legacy}.
+"""
+
+import logging as py_logging
+from time import time
+from typing import List, cast
+
+from zope.interface import implementer
+from zope.interface.exceptions import BrokenMethodImplementation
+from zope.interface.verify import verifyObject
+
+from twisted.python import context, log as legacyLog
+from twisted.python.failure import Failure
+from twisted.trial import unittest
+from .._format import formatEvent
+from .._interfaces import ILogObserver, LogEvent
+from .._legacy import LegacyLogObserverWrapper, publishToNewObserver
+from .._levels import LogLevel
+
+
+class LegacyLogObserverWrapperTests(unittest.TestCase):
+    """
+    Tests for L{LegacyLogObserverWrapper}.
+    """
+
+    def test_interface(self) -> None:
+        """
+        L{LegacyLogObserverWrapper} is an L{ILogObserver}.
+        """
+        legacyObserver = cast(legacyLog.ILogObserver, lambda e: None)
+        observer = LegacyLogObserverWrapper(legacyObserver)
+        try:
+            verifyObject(ILogObserver, observer)
+        except BrokenMethodImplementation as e:
+            self.fail(e)
+
+    def test_repr(self) -> None:
+        """
+        L{LegacyLogObserverWrapper} returns the expected string.
+        """
+
+        @implementer(legacyLog.ILogObserver)
+        class LegacyObserver:
+            def __repr__(self) -> str:
+                return "<Legacy Observer>"
+
+            def __call__(self, eventDict: legacyLog.EventDict) -> None:
+                return
+
+        observer = LegacyLogObserverWrapper(LegacyObserver())
+
+        self.assertEqual(repr(observer), "LegacyLogObserverWrapper(<Legacy Observer>)")
+
+    def observe(self, event: LogEvent) -> LogEvent:
+        """
+        Send an event to a wrapped legacy observer and capture the event as
+        seen by that observer.
+
+        @param event: an event
+
+        @return: the event as observed by the legacy wrapper
+        """
+        events: List[LogEvent] = []
+
+        legacyObserver = cast(legacyLog.ILogObserver, lambda e: events.append(e))
+        observer = LegacyLogObserverWrapper(legacyObserver)
+        observer(event)
+        self.assertEqual(len(events), 1)
+
+        return events[0]
+
+    def forwardAndVerify(self, event: LogEvent) -> LogEvent:
+        """
+        Send an event to a wrapped legacy observer and verify that its data is
+        preserved.
+
+        @param event: an event
+
+        @return: the event as observed by the legacy wrapper
+        """
+        # Make sure keys that are expected by the logging system are present
+        event.setdefault("log_time", time())
+        event.setdefault("log_system", "-")
+        event.setdefault("log_level", LogLevel.info)
+
+        # Send a copy: don't mutate me, bro
+        observed = self.observe(dict(event))
+
+        # Don't expect modifications
+        for key, value in event.items():
+            self.assertIn(key, observed)
+
+        return observed
+
+    def test_forward(self) -> None:
+        """
+        Basic forwarding: event keys as observed by a legacy observer are the
+        same.
+        """
+        self.forwardAndVerify(dict(foo=1, bar=2))
+
+    def test_time(self) -> None:
+        """
+        The new-style C{"log_time"} key is copied to the old-style C{"time"}
+        key.
+        """
+        stamp = time()
+        event = self.forwardAndVerify(dict(log_time=stamp))
+        self.assertEqual(event["time"], stamp)
+
+    def test_timeAlreadySet(self) -> None:
+        """
+        The new-style C{"log_time"} key does not step on a pre-existing
+        old-style C{"time"} key.
+        """
+        stamp = time()
+        event = self.forwardAndVerify(dict(log_time=stamp + 1, time=stamp))
+        self.assertEqual(event["time"], stamp)
+
+    def test_system(self) -> None:
+        """
+        The new-style C{"log_system"} key is copied to the old-style
+        C{"system"} key.
+        """
+        event = self.forwardAndVerify(dict(log_system="foo"))
+        self.assertEqual(event["system"], "foo")
+
+    def test_systemAlreadySet(self) -> None:
+        """
+        The new-style C{"log_system"} key does not step on a pre-existing
+        old-style C{"system"} key.
+        """
+        event = self.forwardAndVerify(dict(log_system="foo", system="bar"))
+        self.assertEqual(event["system"], "bar")
+
+    def test_noSystem(self) -> None:
+        """
+        If the new-style C{"log_system"} key is absent, the old-style
+        C{"system"} key is set to C{"-"}.
+        """
+        # Don't use forwardAndVerify(), since that sets log_system.
+        event = dict(log_time=time(), log_level=LogLevel.info)
+        observed = self.observe(dict(event))
+        self.assertEqual(observed["system"], "-")
+
+    def test_levelNotChange(self) -> None:
+        """
+        If explicitly set, the C{isError} key will be preserved when forwarding
+        from a new-style logging emitter to a legacy logging observer,
+        regardless of log level.
+        """
+        self.forwardAndVerify(dict(log_level=LogLevel.info, isError=1))
+        self.forwardAndVerify(dict(log_level=LogLevel.warn, isError=1))
+        self.forwardAndVerify(dict(log_level=LogLevel.error, isError=0))
+        self.forwardAndVerify(dict(log_level=LogLevel.critical, isError=0))
+
+    def test_pythonLogLevelNotSet(self) -> None:
+        """
+        The new-style C{"log_level"} key is not translated to the old-style
+        C{"logLevel"} key.
+
+        Events are forwarded from the old module from to new module and are
+        then seen by old-style observers.
+        We don't want to add unexpected keys to old-style events.
+        """
+        event = self.forwardAndVerify(dict(log_level=LogLevel.info))
+        self.assertNotIn("logLevel", event)
+
+    def test_stringPythonLogLevel(self) -> None:
+        """
+        If a stdlib log level was provided as a string (eg. C{"WARNING"}) in
+        the legacy "logLevel" key, it does not get converted to a number.
+        The documentation suggested that numerical values should be used but
+        this was not a requirement.
+        """
+        event = self.forwardAndVerify(
+            dict(
+                logLevel="WARNING",  # py_logging.WARNING is 30
+            )
+        )
+        self.assertEqual(event["logLevel"], "WARNING")
+
+    def test_message(self) -> None:
+        """
+        The old-style C{"message"} key is added, even if no new-style
+        C{"log_format"} is given, as it is required, but may be empty.
+        """
+        event = self.forwardAndVerify(dict())
+        self.assertEqual(event["message"], ())  # "message" is a tuple
+
+    def test_messageAlreadySet(self) -> None:
+        """
+        The old-style C{"message"} key is not modified if it already exists.
+        """
+        event = self.forwardAndVerify(dict(message=("foo", "bar")))
+        self.assertEqual(event["message"], ("foo", "bar"))
+
+    def test_format(self) -> None:
+        """
+        Formatting is translated such that text is rendered correctly, even
+        though old-style logging doesn't use PEP 3101 formatting.
+        """
+        event = self.forwardAndVerify(dict(log_format="Hello, {who}!", who="world"))
+        self.assertEqual(legacyLog.textFromEventDict(event), "Hello, world!")
+
+    def test_formatMessage(self) -> None:
+        """
+        Using the message key, which is special in old-style, works for
+        new-style formatting.
+        """
+        event = self.forwardAndVerify(
+            dict(log_format="Hello, {message}!", message="world")
+        )
+        self.assertEqual(legacyLog.textFromEventDict(event), "Hello, world!")
+
+    def test_formatAlreadySet(self) -> None:
+        """
+        Formatting is not altered if the old-style C{"format"} key already
+        exists.
+        """
+        event = self.forwardAndVerify(dict(log_format="Hello!", format="Howdy!"))
+        self.assertEqual(legacyLog.textFromEventDict(event), "Howdy!")
+
+    def eventWithFailure(self, **values: object) -> LogEvent:
+        """
+        Create a new-style event with a captured failure.
+
+        @param values: Additional values to include in the event.
+
+        @return: the new event
+        """
+        failure = Failure(RuntimeError("nyargh!"))
+        return self.forwardAndVerify(
+            dict(log_failure=failure, log_format="oopsie...", **values)
+        )
+
+    def test_failure(self) -> None:
+        """
+        Captured failures in the new style set the old-style C{"failure"},
+        C{"isError"}, and C{"why"} keys.
+        """
+        event = self.eventWithFailure()
+        self.assertIs(event["failure"], event["log_failure"])
+        self.assertTrue(event["isError"])
+        self.assertEqual(event["why"], "oopsie...")
+
+    def test_failureAlreadySet(self) -> None:
+        """
+        Captured failures in the new style do not step on a pre-existing
+        old-style C{"failure"} key.
+        """
+        failure = Failure(RuntimeError("Weak salsa!"))
+        event = self.eventWithFailure(failure=failure)
+        self.assertIs(event["failure"], failure)
+
+    def test_isErrorAlreadySet(self) -> None:
+        """
+        Captured failures in the new style do not step on a pre-existing
+        old-style C{"isError"} key.
+        """
+        event = self.eventWithFailure(isError=0)
+        self.assertEqual(event["isError"], 0)
+
+    def test_whyAlreadySet(self) -> None:
+        """
+        Captured failures in the new style do not step on a pre-existing
+        old-style C{"failure"} key.
+        """
+        event = self.eventWithFailure(why="blah")
+        self.assertEqual(event["why"], "blah")
+
+
+class PublishToNewObserverTests(unittest.TestCase):
+    """
+    Tests for L{publishToNewObserver}.
+    """
+
+    def setUp(self) -> None:
+        self.events: List[LogEvent] = []
+        self.observer = cast(ILogObserver, self.events.append)
+
+    def legacyEvent(self, *message: str, **values: object) -> legacyLog.EventDict:
+        """
+        Return a basic old-style event as would be created by L{legacyLog.msg}.
+
+        @param message: a message event value in the legacy event format
+        @param values: additional event values in the legacy event format
+
+        @return: a legacy event
+        """
+        event = (context.get(legacyLog.ILogContext) or {}).copy()
+        event.update(values)
+        event["message"] = message
+        event["time"] = time()
+        if "isError" not in event:
+            event["isError"] = 0
+        return event
+
+    def test_observed(self) -> None:
+        """
+        The observer is called exactly once.
+        """
+        publishToNewObserver(
+            self.observer, self.legacyEvent(), legacyLog.textFromEventDict
+        )
+        self.assertEqual(len(self.events), 1)
+
+    def test_time(self) -> None:
+        """
+        The old-style C{"time"} key is copied to the new-style C{"log_time"}
+        key.
+        """
+        publishToNewObserver(
+            self.observer, self.legacyEvent(), legacyLog.textFromEventDict
+        )
+        self.assertEqual(self.events[0]["log_time"], self.events[0]["time"])
+
+    def test_message(self) -> None:
+        """
+        A published old-style event should format as text in the same way as
+        the given C{textFromEventDict} callable would format it.
+        """
+
+        def textFromEventDict(event: LogEvent) -> str:
+            return "".join(reversed(" ".join(event["message"])))
+
+        event = self.legacyEvent("Hello,", "world!")
+        text = textFromEventDict(event)
+
+        publishToNewObserver(self.observer, event, textFromEventDict)
+        self.assertEqual(formatEvent(self.events[0]), text)
+
+    def test_defaultLogLevel(self) -> None:
+        """
+        Published event should have log level of L{LogLevel.info}.
+        """
+        publishToNewObserver(
+            self.observer, self.legacyEvent(), legacyLog.textFromEventDict
+        )
+        self.assertEqual(self.events[0]["log_level"], LogLevel.info)
+
+    def test_isError(self) -> None:
+        """
+        If C{"isError"} is set to C{1} (true) on the legacy event, the
+        C{"log_level"} key should get set to L{LogLevel.critical}.
+        """
+        publishToNewObserver(
+            self.observer, self.legacyEvent(isError=1), legacyLog.textFromEventDict
+        )
+        self.assertEqual(self.events[0]["log_level"], LogLevel.critical)
+
+    def test_stdlibLogLevel(self) -> None:
+        """
+        If the old-style C{"logLevel"} key is set to a standard library logging
+        level, using a predefined (L{int}) constant, the new-style
+        C{"log_level"} key should get set to the corresponding log level.
+        """
+        publishToNewObserver(
+            self.observer,
+            self.legacyEvent(logLevel=py_logging.WARNING),
+            legacyLog.textFromEventDict,
+        )
+        self.assertEqual(self.events[0]["log_level"], LogLevel.warn)
+
+    def test_stdlibLogLevelWithString(self) -> None:
+        """
+        If the old-style C{"logLevel"} key is set to a standard library logging
+        level, using a string value, the new-style C{"log_level"} key should
+        get set to the corresponding log level.
+        """
+        publishToNewObserver(
+            self.observer,
+            self.legacyEvent(logLevel="WARNING"),
+            legacyLog.textFromEventDict,
+        )
+        self.assertEqual(self.events[0]["log_level"], LogLevel.warn)
+
+    def test_stdlibLogLevelWithGarbage(self) -> None:
+        """
+        If the old-style C{"logLevel"} key is set to a standard library logging
+        level, using an unknown value, the new-style C{"log_level"} key should
+        not get set.
+        """
+        publishToNewObserver(
+            self.observer,
+            self.legacyEvent(logLevel="Foo!!!!!"),
+            legacyLog.textFromEventDict,
+        )
+        self.assertNotIn("log_level", self.events[0])
+
+    def test_defaultNamespace(self) -> None:
+        """
+        Published event should have a namespace of C{"log_legacy"} to indicate
+        that it was forwarded from legacy logging.
+        """
+        publishToNewObserver(
+            self.observer, self.legacyEvent(), legacyLog.textFromEventDict
+        )
+        self.assertEqual(self.events[0]["log_namespace"], "log_legacy")
+
+    def test_system(self) -> None:
+        """
+        The old-style C{"system"} key is copied to the new-style
+        C{"log_system"} key.
+        """
+        publishToNewObserver(
+            self.observer, self.legacyEvent(), legacyLog.textFromEventDict
+        )
+        self.assertEqual(self.events[0]["log_system"], self.events[0]["system"])

backend/lib/python3.12/site-packages/twisted/logger/test/test_levels.py

@@ -0,0 +1,34 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._levels}.
+"""
+
+from twisted.trial import unittest
+from .._levels import InvalidLogLevelError, LogLevel
+
+
+class LogLevelTests(unittest.TestCase):
+    """
+    Tests for L{LogLevel}.
+    """
+
+    def test_levelWithName(self) -> None:
+        """
+        Look up log level by name.
+        """
+        for level in LogLevel.iterconstants():
+            self.assertIs(LogLevel.levelWithName(level.name), level)
+
+    def test_levelWithInvalidName(self) -> None:
+        """
+        You can't make up log level names.
+        """
+        bogus = "*bogus*"
+        try:
+            LogLevel.levelWithName(bogus)
+        except InvalidLogLevelError as e:
+            self.assertIs(e.level, bogus)
+        else:
+            self.fail("Expected InvalidLogLevelError.")

backend/lib/python3.12/site-packages/twisted/logger/test/test_logger.py

@@ -0,0 +1,354 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._logger}.
+"""
+
+from typing import List, Optional, Type, cast
+
+from zope.interface import implementer
+
+from constantly import NamedConstant
+
+from twisted.python.failure import Failure
+from twisted.trial import unittest
+from .._format import formatEvent
+from .._global import globalLogPublisher
+from .._interfaces import ILogObserver, LogEvent
+from .._levels import InvalidLogLevelError, LogLevel
+from .._logger import Logger
+
+
+class TestLogger(Logger):
+    """
+    L{Logger} with an overridden C{emit} method that keeps track of received
+    events.
+    """
+
+    def emit(
+        self, level: NamedConstant, format: Optional[str] = None, **kwargs: object
+    ) -> None:
+        @implementer(ILogObserver)
+        def observer(event: LogEvent) -> None:
+            self.event = event
+
+        globalLogPublisher.addObserver(observer)
+        try:
+            Logger.emit(self, level, format, **kwargs)
+        finally:
+            globalLogPublisher.removeObserver(observer)
+
+        self.emitted = {
+            "level": level,
+            "format": format,
+            "kwargs": kwargs,
+        }
+
+
+class LogComposedObject:
+    """
+    A regular object, with a logger attached.
+    """
+
+    log = TestLogger()
+
+    def __init__(self, state: Optional[str] = None) -> None:
+        self.state = state
+
+    def __str__(self) -> str:
+        return f"<LogComposedObject {self.state}>"
+
+
+class LoggerTests(unittest.TestCase):
+    """
+    Tests for L{Logger}.
+    """
+
+    def test_repr(self) -> None:
+        """
+        repr() on Logger
+        """
+        namespace = "bleargh"
+        log = Logger(namespace)
+        self.assertEqual(repr(log), f"<Logger {repr(namespace)}>")
+
+    def test_namespaceDefault(self) -> None:
+        """
+        Default namespace is module name.
+        """
+        log = Logger()
+        self.assertEqual(log.namespace, __name__)
+
+    def test_namespaceOMGItsTooHard(self) -> None:
+        """
+        Default namespace is C{"<unknown>"} when a logger is created from a
+        context in which is can't be determined automatically and no namespace
+        was specified.
+        """
+        result: List[Logger] = []
+        exec(
+            "result.append(Logger())",
+            dict(Logger=Logger),
+            locals(),
+        )
+        self.assertEqual(result[0].namespace, "<unknown>")
+
+    def test_namespaceAttribute(self) -> None:
+        """
+        Default namespace for classes using L{Logger} as a descriptor is the
+        class name they were retrieved from.
+        """
+        obj = LogComposedObject()
+
+        expectedNamespace = "{}.{}".format(
+            obj.__module__,
+            obj.__class__.__name__,
+        )
+
+        self.assertEqual(cast(TestLogger, obj.log).namespace, expectedNamespace)
+        self.assertEqual(
+            cast(Type[TestLogger], LogComposedObject.log).namespace, expectedNamespace
+        )
+        self.assertIs(
+            cast(Type[TestLogger], LogComposedObject.log).source, LogComposedObject
+        )
+        self.assertIs(cast(TestLogger, obj.log).source, obj)
+        self.assertIsNone(Logger().source)
+
+    def test_descriptorObserver(self) -> None:
+        """
+        When used as a descriptor, the observer is propagated.
+        """
+        observed: List[LogEvent] = []
+
+        class MyObject:
+            log = Logger(observer=cast(ILogObserver, observed.append))
+
+        MyObject.log.info("hello")
+        self.assertEqual(len(observed), 1)
+        self.assertEqual(observed[0]["log_format"], "hello")
+
+    def test_sourceAvailableForFormatting(self) -> None:
+        """
+        On instances that have a L{Logger} class attribute, the C{log_source}
+        key is available to format strings.
+        """
+        obj = LogComposedObject("hello")
+        log = cast(TestLogger, obj.log)
+        log.error("Hello, {log_source}.")
+
+        self.assertIn("log_source", log.event)
+        self.assertEqual(log.event["log_source"], obj)
+
+        stuff = formatEvent(log.event)
+        self.assertIn("Hello, <LogComposedObject hello>.", stuff)
+
+    def test_basicLogger(self) -> None:
+        """
+        Test that log levels and messages are emitted correctly for
+        Logger.
+        """
+        log = TestLogger()
+
+        for level in LogLevel.iterconstants():
+            format = "This is a {level_name} message"
+            message = format.format(level_name=level.name)
+
+            logMethod = getattr(log, level.name)
+            logMethod(format, junk=message, level_name=level.name)
+
+            # Ensure that test_emit got called with expected arguments
+            self.assertEqual(log.emitted["level"], level)
+            self.assertEqual(log.emitted["format"], format)
+            self.assertEqual(log.emitted["kwargs"]["junk"], message)
+
+            self.assertTrue(hasattr(log, "event"), "No event observed.")
+
+            self.assertEqual(log.event["log_format"], format)
+            self.assertEqual(log.event["log_level"], level)
+            self.assertEqual(log.event["log_namespace"], __name__)
+            self.assertIsNone(log.event["log_source"])
+            self.assertEqual(log.event["junk"], message)
+
+            self.assertEqual(formatEvent(log.event), message)
+
+    def test_sourceOnClass(self) -> None:
+        """
+        C{log_source} event key refers to the class.
+        """
+
+        @implementer(ILogObserver)
+        def observer(event: LogEvent) -> None:
+            self.assertEqual(event["log_source"], Thingo)
+
+        class Thingo:
+            log = TestLogger(observer=observer)
+
+        cast(TestLogger, Thingo.log).info()
+
+    def test_sourceOnInstance(self) -> None:
+        """
+        C{log_source} event key refers to the instance.
+        """
+
+        @implementer(ILogObserver)
+        def observer(event: LogEvent) -> None:
+            self.assertEqual(event["log_source"], thingo)
+
+        class Thingo:
+            log = TestLogger(observer=observer)
+
+        thingo = Thingo()
+        cast(TestLogger, thingo.log).info()
+
+    def test_sourceUnbound(self) -> None:
+        """
+        C{log_source} event key is L{None}.
+        """
+
+        @implementer(ILogObserver)
+        def observer(event: LogEvent) -> None:
+            self.assertIsNone(event["log_source"])
+
+        log = TestLogger(observer=observer)
+        log.info()
+
+    def test_defaultFailure(self) -> None:
+        """
+        Test that log.failure() emits the right data.
+        """
+        log = TestLogger()
+        try:
+            raise RuntimeError("baloney!")
+        except RuntimeError:
+            log.failure("Whoops")
+
+        errors = self.flushLoggedErrors(RuntimeError)
+        self.assertEqual(len(errors), 1)
+
+        self.assertEqual(log.emitted["level"], LogLevel.critical)
+        self.assertEqual(log.emitted["format"], "Whoops")
+
+    def test_conflictingKwargs(self) -> None:
+        """
+        Make sure that kwargs conflicting with args don't pass through.
+        """
+        log = TestLogger()
+
+        log.warn(
+            "*",
+            log_format="#",
+            log_level=LogLevel.error,
+            log_namespace="*namespace*",
+            log_source="*source*",
+        )
+
+        self.assertEqual(log.event["log_format"], "*")
+        self.assertEqual(log.event["log_level"], LogLevel.warn)
+        self.assertEqual(log.event["log_namespace"], log.namespace)
+        self.assertIsNone(log.event["log_source"])
+
+    def test_logInvalidLogLevel(self) -> None:
+        """
+        Test passing in a bogus log level to C{emit()}.
+        """
+        log = TestLogger()
+
+        log.emit("*bogus*")
+
+        errors = self.flushLoggedErrors(InvalidLogLevelError)
+        self.assertEqual(len(errors), 1)
+
+    def test_trace(self) -> None:
+        """
+        Tracing keeps track of forwarding to the publisher.
+        """
+
+        @implementer(ILogObserver)
+        def publisher(event: LogEvent) -> None:
+            observer(event)
+
+        @implementer(ILogObserver)
+        def observer(event: LogEvent) -> None:
+            self.assertEqual(event["log_trace"], [(log, publisher)])
+
+        log = TestLogger(observer=publisher)
+        log.info("Hello.", log_trace=[])
+
+    def test_failuresHandled(self) -> None:
+        """
+        The L{Logger.failuresHandled} context manager catches any
+        L{BaseException} and converts it into a logged L{Failure}.
+        """
+        events = []
+
+        @implementer(ILogObserver)
+        def logged(event: LogEvent) -> None:
+            events.append(event)
+
+        log = TestLogger(observer=logged)
+        reprd = 0
+
+        class Reprable:
+            def __repr__(self) -> str:
+                nonlocal reprd
+                reprd += 1
+                return f"<repr {reprd}>"
+
+        with log.failuresHandled(
+            "while testing failure handling for {value}", value=Reprable()
+        ) as operation:
+            1 / 0
+        self.assertEqual(operation.succeeded, False)
+        self.assertEqual(operation.failed, True)
+        self.assertEqual(len(events), 1)
+        [logged] = events
+        events[:] = []
+        f: Failure = logged["log_failure"]
+        self.assertEqual(reprd, 0)
+        self.assertEqual(
+            formatEvent(logged), "while testing failure handling for <repr 1>"
+        )
+        self.assertEqual(reprd, 1)
+        self.assertEqual(f.type, ZeroDivisionError)
+        with log.failuresHandled("succeeding for {value}", value=Reprable()) as op2:
+            self.assertEqual(op2.succeeded, False)
+            self.assertEqual(op2.failed, False)
+        self.assertEqual(reprd, 1)
+        self.assertEqual(op2.succeeded, True)
+        self.assertEqual(op2.failed, False)
+
+    def test_failureHandler(self) -> None:
+        """
+        The L{Logger.failureHandler} context manager can safely be shared
+        amongst multiple invocations and converts L{BaseException} into logged
+        L{Failure}s.
+        """
+        events = []
+
+        @implementer(ILogObserver)
+        def logged(event: LogEvent) -> None:
+            events.append(event)
+
+        log = TestLogger(observer=logged)
+
+        failureHandler = log.failureHandler("hello")
+        success = False
+        with failureHandler as fh:
+            success = True
+        self.assertIs(fh, None)
+        self.assertEqual(success, True)
+        self.assertEqual(events, [])
+        success = False
+
+        def raisebase() -> None:
+            raise KeyboardInterrupt()
+
+        with failureHandler as fh:
+            raisebase()
+
+        self.assertEqual(len(events), 1)
+        [logged] = events
+        f = logged["log_failure"]
+        self.assertEqual(f.type, KeyboardInterrupt)

backend/lib/python3.12/site-packages/twisted/logger/test/test_observer.py

@@ -0,0 +1,192 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._observer}.
+"""
+
+from typing import Dict, List, Tuple, cast
+
+from zope.interface import implementer
+from zope.interface.exceptions import BrokenMethodImplementation
+from zope.interface.verify import verifyObject
+
+from twisted.trial import unittest
+from .._interfaces import ILogObserver, LogEvent
+from .._logger import Logger
+from .._observer import LogPublisher
+
+
+class LogPublisherTests(unittest.TestCase):
+    """
+    Tests for L{LogPublisher}.
+    """
+
+    def test_interface(self) -> None:
+        """
+        L{LogPublisher} is an L{ILogObserver}.
+        """
+        publisher = LogPublisher()
+        try:
+            verifyObject(ILogObserver, publisher)
+        except BrokenMethodImplementation as e:
+            self.fail(e)
+
+    def test_observers(self) -> None:
+        """
+        L{LogPublisher.observers} returns the observers.
+        """
+        o1 = cast(ILogObserver, lambda e: None)
+        o2 = cast(ILogObserver, lambda e: None)
+
+        publisher = LogPublisher(o1, o2)
+        self.assertEqual({o1, o2}, set(publisher._observers))
+
+    def test_addObserver(self) -> None:
+        """
+        L{LogPublisher.addObserver} adds an observer.
+        """
+        o1 = cast(ILogObserver, lambda e: None)
+        o2 = cast(ILogObserver, lambda e: None)
+        o3 = cast(ILogObserver, lambda e: None)
+
+        publisher = LogPublisher(o1, o2)
+        publisher.addObserver(o3)
+        self.assertEqual({o1, o2, o3}, set(publisher._observers))
+
+    def test_addObserverNotCallable(self) -> None:
+        """
+        L{LogPublisher.addObserver} refuses to add an observer that's
+        not callable.
+        """
+        publisher = LogPublisher()
+        self.assertRaises(TypeError, publisher.addObserver, object())
+
+    def test_removeObserver(self) -> None:
+        """
+        L{LogPublisher.removeObserver} removes an observer.
+        """
+        o1 = cast(ILogObserver, lambda e: None)
+        o2 = cast(ILogObserver, lambda e: None)
+        o3 = cast(ILogObserver, lambda e: None)
+
+        publisher = LogPublisher(o1, o2, o3)
+        publisher.removeObserver(o2)
+        self.assertEqual({o1, o3}, set(publisher._observers))
+
+    def test_removeObserverNotRegistered(self) -> None:
+        """
+        L{LogPublisher.removeObserver} removes an observer that is not
+        registered.
+        """
+        o1 = cast(ILogObserver, lambda e: None)
+        o2 = cast(ILogObserver, lambda e: None)
+        o3 = cast(ILogObserver, lambda e: None)
+
+        publisher = LogPublisher(o1, o2)
+        publisher.removeObserver(o3)
+        self.assertEqual({o1, o2}, set(publisher._observers))
+
+    def test_fanOut(self) -> None:
+        """
+        L{LogPublisher} calls its observers.
+        """
+        event = dict(foo=1, bar=2)
+
+        events1: List[LogEvent] = []
+        events2: List[LogEvent] = []
+        events3: List[LogEvent] = []
+
+        o1 = cast(ILogObserver, events1.append)
+        o2 = cast(ILogObserver, events2.append)
+        o3 = cast(ILogObserver, events3.append)
+
+        publisher = LogPublisher(o1, o2, o3)
+        publisher(event)
+        self.assertIn(event, events1)
+        self.assertIn(event, events2)
+        self.assertIn(event, events3)
+
+    def test_observerRaises(self) -> None:
+        """
+        Observer raises an exception during fan out: a failure is logged, but
+        not re-raised.  Life goes on.
+        """
+        event = dict(foo=1, bar=2)
+        exception = RuntimeError("ARGH! EVIL DEATH!")
+
+        events: List[LogEvent] = []
+
+        @implementer(ILogObserver)
+        def observer(event: LogEvent) -> None:
+            shouldRaise = not events
+            events.append(event)
+            if shouldRaise:
+                raise exception
+
+        collector: List[LogEvent] = []
+
+        publisher = LogPublisher(observer, cast(ILogObserver, collector.append))
+        publisher(event)
+
+        # Verify that the observer saw my event
+        self.assertIn(event, events)
+
+        # Verify that the observer raised my exception
+        errors = [e["log_failure"] for e in collector if "log_failure" in e]
+        self.assertEqual(len(errors), 1)
+        self.assertIs(errors[0].value, exception)
+        # Make sure the exceptional observer does not receive its own error.
+        self.assertEqual(len(events), 1)
+
+    def test_observerRaisesAndLoggerHatesMe(self) -> None:
+        """
+        Observer raises an exception during fan out and the publisher's Logger
+        pukes when the failure is reported.  The exception does not propagate
+        back to the caller.
+        """
+        event = dict(foo=1, bar=2)
+        exception = RuntimeError("ARGH! EVIL DEATH!")
+
+        @implementer(ILogObserver)
+        def observer(event: LogEvent) -> None:
+            raise RuntimeError("Sad panda")
+
+        class GurkLogger(Logger):
+            def failure(self, *args: object, **kwargs: object) -> None:
+                raise exception
+
+        publisher = LogPublisher(observer)
+        publisher.log = GurkLogger()
+        publisher(event)
+
+        # Here, the lack of an exception thus far is a success, of sorts
+
+    def test_trace(self) -> None:
+        """
+        Tracing keeps track of forwarding to observers.
+        """
+        event = dict(foo=1, bar=2, log_trace=[])
+
+        traces: Dict[int, Tuple[Tuple[Logger, ILogObserver]]] = {}
+
+        # Copy trace to a tuple; otherwise, both observers will store the same
+        # mutable list, and we won't be able to see o1's view distinctly.
+
+        @implementer(ILogObserver)
+        def o1(e: LogEvent) -> None:
+            traces.setdefault(
+                1, cast(Tuple[Tuple[Logger, ILogObserver]], tuple(e["log_trace"]))
+            )
+
+        @implementer(ILogObserver)
+        def o2(e: LogEvent) -> None:
+            traces.setdefault(
+                2, cast(Tuple[Tuple[Logger, ILogObserver]], tuple(e["log_trace"]))
+            )
+
+        publisher = LogPublisher(o1, o2)
+        publisher(event)
+
+        self.assertEqual(traces[1], ((publisher, o1),))
+        self.assertEqual(traces[2], ((publisher, o1), (publisher, o2)))

backend/lib/python3.12/site-packages/twisted/logger/test/test_stdlib.py

@@ -0,0 +1,293 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._format}.
+"""
+from __future__ import annotations
+
+import logging as py_logging
+import sys
+from inspect import getsourcefile
+from io import BytesIO, TextIOWrapper
+from logging import Formatter, LogRecord, StreamHandler, getLogger
+from typing import List, Optional, Tuple
+
+from zope.interface.exceptions import BrokenMethodImplementation
+from zope.interface.verify import verifyObject
+
+from twisted.python.compat import currentframe
+from twisted.python.failure import Failure
+from twisted.trial import unittest
+from .._interfaces import ILogObserver, LogEvent
+from .._levels import LogLevel
+from .._stdlib import STDLibLogObserver
+
+
+def nextLine() -> Tuple[Optional[str], int]:
+    """
+    Retrive the file name and line number immediately after where this function
+    is called.
+
+    @return: the file name and line number
+    """
+    caller = currentframe(1)
+    return (
+        getsourcefile(sys.modules[caller.f_globals["__name__"]]),
+        caller.f_lineno + 1,
+    )
+
+
+class StdlibLoggingContainer:
+    """
+    Continer for a test configuration of stdlib logging objects.
+    """
+
+    def __init__(self) -> None:
+        self.rootLogger = getLogger("")
+
+        self.originalLevel = self.rootLogger.getEffectiveLevel()
+        self.rootLogger.setLevel(py_logging.DEBUG)
+
+        self.bufferedHandler = BufferedHandler()
+        self.rootLogger.addHandler(self.bufferedHandler)
+
+        self.streamHandler, self.output = handlerAndBytesIO()
+        self.rootLogger.addHandler(self.streamHandler)
+
+    def close(self) -> None:
+        """
+        Close the logger.
+        """
+        self.rootLogger.setLevel(self.originalLevel)
+        self.rootLogger.removeHandler(self.bufferedHandler)
+        self.rootLogger.removeHandler(self.streamHandler)
+        self.streamHandler.close()
+        self.output.close()
+
+    def outputAsText(self) -> str:
+        """
+        Get the output to the underlying stream as text.
+
+        @return: the output text
+        """
+        return self.output.getvalue().decode("utf-8")
+
+
+class STDLibLogObserverTests(unittest.TestCase):
+    """
+    Tests for L{STDLibLogObserver}.
+    """
+
+    def test_interface(self) -> None:
+        """
+        L{STDLibLogObserver} is an L{ILogObserver}.
+        """
+        observer = STDLibLogObserver()
+        try:
+            verifyObject(ILogObserver, observer)
+        except BrokenMethodImplementation as e:
+            self.fail(e)
+
+    def py_logger(self) -> StdlibLoggingContainer:
+        """
+        Create a logging object we can use to test with.
+
+        @return: a stdlib-style logger
+        """
+        logger = StdlibLoggingContainer()
+        self.addCleanup(logger.close)
+        return logger
+
+    def logEvent(self, *events: LogEvent) -> Tuple[List[LogRecord], str]:
+        """
+        Send one or more events to Python's logging module, and capture the
+        emitted L{LogRecord}s and output stream as a string.
+
+        @param events: events
+
+        @return: a tuple: (records, output)
+        """
+        pl = self.py_logger()
+        observer = STDLibLogObserver(
+            # Add 1 to default stack depth to skip *this* frame, since
+            # tests will want to know about their own frames.
+            stackDepth=STDLibLogObserver.defaultStackDepth
+            + 1
+        )
+
+        for event in events:
+            observer(event)
+
+        return pl.bufferedHandler.records, pl.outputAsText()
+
+    def test_name(self) -> None:
+        """
+        Logger name.
+        """
+        records, output = self.logEvent({})
+
+        self.assertEqual(len(records), 1)
+        self.assertEqual(records[0].name, "twisted")
+
+    def test_levels(self) -> None:
+        """
+        Log levels.
+        """
+        levelMapping = {
+            None: py_logging.INFO,  # Default
+            LogLevel.debug: py_logging.DEBUG,
+            LogLevel.info: py_logging.INFO,
+            LogLevel.warn: py_logging.WARNING,
+            LogLevel.error: py_logging.ERROR,
+            LogLevel.critical: py_logging.CRITICAL,
+        }
+
+        # Build a set of events for each log level
+        events = []
+        for level, pyLevel in levelMapping.items():
+            event = {}
+
+            # Set the log level on the event, except for default
+            if level is not None:
+                event["log_level"] = level
+
+            # Remember the Python log level we expect to see for this
+            # event (as an int)
+            event["py_levelno"] = int(pyLevel)
+
+            events.append(event)
+
+        records, output = self.logEvent(*events)
+        self.assertEqual(len(records), len(levelMapping))
+
+        # Check that each event has the correct level
+        for i in range(len(records)):
+            self.assertEqual(records[i].levelno, events[i]["py_levelno"])
+
+    def test_callerInfo(self) -> None:
+        """
+        C{pathname}, C{lineno}, C{exc_info}, C{func} is set properly on
+        records.
+        """
+        filename, logLine = nextLine()
+        records, output = self.logEvent({})
+
+        self.assertEqual(len(records), 1)
+        self.assertEqual(records[0].pathname, filename)
+        self.assertEqual(records[0].lineno, logLine)
+        self.assertIsNone(records[0].exc_info)
+
+        # Attribute "func" is missing from record, which is weird because it's
+        # documented.
+        # self.assertEqual(records[0].func, "test_callerInfo")
+
+    def test_basicFormat(self) -> None:
+        """
+        Basic formattable event passes the format along correctly.
+        """
+        event = dict(log_format="Hello, {who}!", who="dude")
+        records, output = self.logEvent(event)
+
+        self.assertEqual(len(records), 1)
+        self.assertEqual(str(records[0].msg), "Hello, dude!")
+        self.assertEqual(records[0].args, ())
+
+    def test_basicFormatRendered(self) -> None:
+        """
+        Basic formattable event renders correctly.
+        """
+        event = dict(log_format="Hello, {who}!", who="dude")
+        records, output = self.logEvent(event)
+
+        self.assertEqual(len(records), 1)
+        self.assertTrue(output.endswith(":Hello, dude!\n"), repr(output))
+
+    def test_noFormat(self) -> None:
+        """
+        Event with no format.
+        """
+        records, output = self.logEvent({})
+
+        self.assertEqual(len(records), 1)
+        self.assertEqual(str(records[0].msg), "")
+
+    def test_failure(self) -> None:
+        """
+        An event with a failure logs the failure details as well.
+        """
+
+        def failing_func() -> None:
+            1 / 0
+
+        try:
+            failing_func()
+        except ZeroDivisionError:
+            failure = Failure()
+
+        event = dict(log_format="Hi mom", who="me", log_failure=failure)
+        records, output = self.logEvent(event)
+
+        self.assertEqual(len(records), 1)
+        self.assertIn("Hi mom", output)
+        self.assertIn("in failing_func", output)
+        self.assertIn("ZeroDivisionError", output)
+
+    def test_cleanedFailure(self) -> None:
+        """
+        A cleaned Failure object has a fake traceback object; make sure that
+        logging such a failure still results in the exception details being
+        logged.
+        """
+
+        def failing_func() -> None:
+            1 / 0
+
+        try:
+            failing_func()
+        except ZeroDivisionError:
+            failure = Failure()
+            failure.cleanFailure()
+
+        event = dict(log_format="Hi mom", who="me", log_failure=failure)
+        records, output = self.logEvent(event)
+
+        self.assertEqual(len(records), 1)
+        self.assertIn("Hi mom", output)
+        self.assertIn("in failing_func", output)
+        self.assertIn("ZeroDivisionError", output)
+
+
+def handlerAndBytesIO() -> tuple[StreamHandler[TextIOWrapper], BytesIO]:
+    """
+    Construct a 2-tuple of C{(StreamHandler, BytesIO)} for testing interaction
+    with the 'logging' module.
+
+    @return: handler and io object
+    """
+    output = BytesIO()
+    template = py_logging.BASIC_FORMAT
+    stream = TextIOWrapper(output, encoding="utf-8", newline="\n")
+    formatter = Formatter(template)
+    handler = StreamHandler(stream)
+    handler.setFormatter(formatter)
+    return handler, output
+
+
+class BufferedHandler(py_logging.Handler):
+    """
+    A L{py_logging.Handler} that remembers all logged records in a list.
+    """
+
+    def __init__(self) -> None:
+        """
+        Initialize this L{BufferedHandler}.
+        """
+        py_logging.Handler.__init__(self)
+        self.records: List[LogRecord] = []
+
+    def emit(self, record: LogRecord) -> None:
+        """
+        Remember the record.
+        """
+        self.records.append(record)

backend/lib/python3.12/site-packages/twisted/logger/test/test_util.py

@@ -0,0 +1,139 @@
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Test cases for L{twisted.logger._util}.
+"""
+
+from zope.interface import implementer
+
+from twisted.trial import unittest
+from .._interfaces import ILogObserver, LogEvent
+from .._observer import LogPublisher
+from .._util import formatTrace
+
+
+class UtilTests(unittest.TestCase):
+    """
+    Utility tests.
+    """
+
+    def test_trace(self) -> None:
+        """
+        Tracing keeps track of forwarding done by the publisher.
+        """
+        publisher = LogPublisher()
+
+        event: LogEvent = dict(log_trace=[])
+
+        @implementer(ILogObserver)
+        def o1(e: LogEvent) -> None:
+            pass
+
+        @implementer(ILogObserver)
+        def o2(e: LogEvent) -> None:
+            self.assertIs(e, event)
+            self.assertEqual(
+                e["log_trace"],
+                [
+                    (publisher, o1),
+                    (publisher, o2),
+                    # Event hasn't been sent to o3 yet
+                ],
+            )
+
+        @implementer(ILogObserver)
+        def o3(e: LogEvent) -> None:
+            self.assertIs(e, event)
+            self.assertEqual(
+                e["log_trace"],
+                [
+                    (publisher, o1),
+                    (publisher, o2),
+                    (publisher, o3),
+                ],
+            )
+
+        publisher.addObserver(o1)
+        publisher.addObserver(o2)
+        publisher.addObserver(o3)
+        publisher(event)
+
+    def test_formatTrace(self) -> None:
+        """
+        Format trace as string.
+        """
+        event: LogEvent = dict(log_trace=[])
+
+        @implementer(ILogObserver)
+        def o1(e: LogEvent) -> None:
+            pass
+
+        @implementer(ILogObserver)
+        def o2(e: LogEvent) -> None:
+            pass
+
+        @implementer(ILogObserver)
+        def o3(e: LogEvent) -> None:
+            pass
+
+        @implementer(ILogObserver)
+        def o4(e: LogEvent) -> None:
+            pass
+
+        @implementer(ILogObserver)
+        def o5(e: LogEvent) -> None:
+            pass
+
+        o1.name = "root/o1"
+        o2.name = "root/p1/o2"
+        o3.name = "root/p1/o3"
+        o4.name = "root/p1/p2/o4"
+        o5.name = "root/o5"
+
+        expectedTrace: str  # populated below
+
+        @implementer(ILogObserver)
+        def testObserver(e: LogEvent) -> None:
+            self.assertIs(e, event)
+            trace = formatTrace(e["log_trace"])
+            self.assertEqual(trace, expectedTrace)
+
+        oTest = testObserver
+
+        p2 = LogPublisher(o4)
+        p1 = LogPublisher(o2, o3, p2)
+
+        p2.name = "root/p1/p2/"  # type: ignore[attr-defined]
+        p1.name = "root/p1/"  # type: ignore[attr-defined]
+
+        root = LogPublisher(o1, p1, o5, oTest)
+        root.name = "root/"  # type: ignore[attr-defined]
+        expectedTraceTemplate = (
+            "{root} ({root.name})\n"
+            "  -> {o1} ({o1.name})\n"
+            "  -> {p1} ({p1.name})\n"
+            "    -> {o2} ({o2.name})\n"
+            "    -> {o3} ({o3.name})\n"
+            "    -> {p2} ({p2.name})\n"
+            "      -> {o4} ({o4.name})\n"
+            "  -> {o5} ({o5.name})\n"
+            "  -> {oTest}\n"
+        )
+
+        # Mypy rightly complains that we're pulling some Shenanigans with all
+        # these 'name' attributes above (LogPublisher does not have any such
+        # attribute, neither does FunctionType) so we split up the 'format'
+        # call so it can't see the attributes being formatted.
+        expectedTrace = expectedTraceTemplate.format(
+            root=root,
+            o1=o1,
+            o2=o2,
+            o3=o3,
+            o4=o4,
+            o5=o5,
+            p1=p1,
+            p2=p2,
+            oTest=oTest,
+        )
+        root(event)