Added method to download subtitles as VTT

src/test/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudStreamExtractorDefaultTest.java

@@ -105,6 +105,6 @@ public class SoundcloudStreamExtractorDefaultTest {
 
     @Test
     public void testGetSubtitles() throws IOException, ExtractionException, JsonParserException {
-        assertTrue(extractor.getSubtitles() != null);
+        assertTrue(extractor.getSubtitlesList() != null);
     }
 }

src/test/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractorDefaultTest.java

@@ -152,7 +152,18 @@ public class YoutubeStreamExtractorDefaultTest {
     }
 
     @Test
-    public void testGetSubtitles() throws IOException, ExtractionException, JsonParserException {
-        assertTrue(extractor.getSubtitles() != null);
+    public void testGetSubtitlesList() throws IOException, ExtractionException, JsonParserException {
+        assertTrue(extractor.getSubtitlesList() != null);
+    }
+
+    @Test
+    public void testDownloadSubtitles() throws Exception {
+        try {
+            extractor.downloadSubtitles(extractor.getSubtitlesList().get("en")[0]);
+            // Video has no subtitles!
+            assert false;
+        } catch (Exception e) {
+            assert true;
+        }
     }
 }

src/test/java/org/schabi/newpipe/extractor/services/youtube/YoutubeStreamExtractorRestrictedTest.java

@@ -106,7 +106,12 @@ public class YoutubeStreamExtractorRestrictedTest {
     }
 
     @Test
-    public void testGetSubtitles() throws IOException, ExtractionException, JsonParserException {
-        assertTrue(extractor.getSubtitles() != null);
+    public void testGetSubtitlesList() throws IOException, ExtractionException, JsonParserException {
+        assertTrue(extractor.getSubtitlesList() != null);
+    }
+
+    @Test
+    public void testDownloadSubtitles() throws Exception {
+        assertTrue(extractor.downloadSubtitles("https://youtu.be/FmG385_uUys?t=174") != null);
     }
 }