RAHHH

backend/lib/python3.12/site-packages/twisted/python/test/test_tzhelper.py

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+# # Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Tests for L{twisted.python._tzhelper}.
+"""
+
+from __future__ import annotations
+
+from os import environ
+
+try:
+    from time import tzset as _tzset
+except ImportError:
+    tzset = None
+else:
+    tzset = _tzset
+
+from datetime import datetime, timedelta
+from time import mktime as mktime_real
+
+from twisted.python._tzhelper import FixedOffsetTimeZone
+from twisted.trial.unittest import SkipTest, TestCase
+
+# On some rare platforms (FreeBSD 8?  I was not able to reproduce
+# on FreeBSD 9) 'mktime' seems to always fail once tzset() has been
+# called more than once in a process lifetime.  I think this is
+# just a platform bug, so let's work around it.  -glyph
+
+
+def mktime(t9: tuple[int, int, int, int, int, int, int, int, int]) -> float:
+    """
+    Call L{mktime_real}, and if it raises L{OverflowError}, catch it and raise
+    SkipTest instead.
+
+    @param t9: A time as a 9-item tuple.
+    @type t9: L{tuple}
+
+    @return: A timestamp.
+    @rtype: L{float}
+    """
+    try:
+        return mktime_real(t9)
+    except OverflowError:
+        raise SkipTest(f"Platform cannot construct time zone for {t9!r}")
+
+
+def setTZ(name: str | None) -> None:
+    """
+    Set time zone.
+
+    @param name: a time zone name
+    @type name: L{str}
+    """
+    if tzset is None:
+        return
+
+    if name is None:
+        try:
+            del environ["TZ"]
+        except KeyError:
+            pass
+    else:
+        environ["TZ"] = name
+    tzset()
+
+
+def addTZCleanup(testCase: TestCase) -> None:
+    """
+    Add cleanup hooks to a test case to reset timezone to original value.
+
+    @param testCase: the test case to add the cleanup to.
+    @type testCase: L{unittest.TestCase}
+    """
+    tzIn = environ.get("TZ", None)
+
+    @testCase.addCleanup
+    def resetTZ() -> None:
+        setTZ(tzIn)
+
+
+class FixedOffsetTimeZoneTests(TestCase):
+    """
+    Tests for L{FixedOffsetTimeZone}.
+    """
+
+    def test_tzinfo(self) -> None:
+        """
+        Test that timezone attributes respect 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, expectedOffsetDST: str, expectedOffsetSTD: str
+        ) -> None:
+            setTZ(name)
+
+            localDST = mktime((2006, 6, 30, 0, 0, 0, 4, 181, 1))
+            localDSTdt = datetime.fromtimestamp(localDST)
+            localSTD = mktime((2007, 1, 31, 0, 0, 0, 2, 31, 0))
+            localSTDdt = datetime.fromtimestamp(localSTD)
+
+            tzDST = FixedOffsetTimeZone.fromLocalTimeStamp(localDST)
+            tzSTD = FixedOffsetTimeZone.fromLocalTimeStamp(localSTD)
+
+            self.assertEqual(tzDST.tzname(localDSTdt), f"UTC{expectedOffsetDST}")
+            self.assertEqual(tzSTD.tzname(localSTDdt), f"UTC{expectedOffsetSTD}")
+
+            self.assertEqual(tzDST.dst(localDSTdt), timedelta(0))
+            self.assertEqual(tzSTD.dst(localSTDdt), timedelta(0))
+
+            def timeDeltaFromOffset(offset: str) -> timedelta:
+                assert len(offset) == 5
+
+                sign = offset[0]
+                hours = int(offset[1:3])
+                minutes = int(offset[3:5])
+
+                if sign == "-":
+                    hours = -hours
+                    minutes = -minutes
+                else:
+                    assert sign == "+"
+
+                return timedelta(hours=hours, minutes=minutes)
+
+            self.assertEqual(
+                tzDST.utcoffset(localDSTdt), timeDeltaFromOffset(expectedOffsetDST)
+            )
+            self.assertEqual(
+                tzSTD.utcoffset(localSTDdt), timeDeltaFromOffset(expectedOffsetSTD)
+            )
+
+        addTZCleanup(self)
+
+        # UTC
+        testForTimeZone("UTC+00", "+0000", "+0000")
+        # West of UTC
+        testForTimeZone("EST+05EDT,M4.1.0,M10.5.0", "-0400", "-0500")
+        # East of UTC
+        testForTimeZone("CEST-01CEDT,M4.1.0,M10.5.0", "+0200", "+0100")
+        # No DST
+        testForTimeZone("CST+06", "-0600", "-0600")