Add test for Eminem channel (it has no "Subscribe" button)

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

@@ -392,6 +392,100 @@ public class YoutubeChannelExtractorTest {
         }
     }
 
+    // this channel has no "Subscribe" button
+    public static class EminemVEVO implements BaseChannelExtractorTest {
+        private static YoutubeChannelExtractor extractor;
+
+        @BeforeClass
+        public static void setUp() throws Exception {
+            NewPipe.init(Downloader.getInstance(), new Localization("GB", "en"));
+            extractor = (YoutubeChannelExtractor) YouTube
+                    .getChannelExtractor("https://www.youtube.com/user/EminemVEVO/");
+            extractor.fetchPage();
+        }
+
+        /*//////////////////////////////////////////////////////////////////////////
+        // Extractor
+        //////////////////////////////////////////////////////////////////////////*/
+
+        @Test
+        public void testServiceId() {
+            assertEquals(YouTube.getServiceId(), extractor.getServiceId());
+        }
+
+        @Test
+        public void testName() throws Exception {
+            assertEquals("EminemVEVO", extractor.getName());
+        }
+
+        @Test
+        public void testId() throws Exception {
+            assertEquals("UC20vb-R_px4CguHzzBPhoyQ", extractor.getId());
+        }
+
+        @Test
+        public void testUrl() throws ParsingException {
+            assertEquals("https://www.youtube.com/channel/UC20vb-R_px4CguHzzBPhoyQ", extractor.getUrl());
+        }
+
+        @Test
+        public void testOriginalUrl() throws ParsingException {
+            assertEquals("https://www.youtube.com/user/EminemVEVO/", extractor.getOriginalUrl());
+        }
+
+        /*//////////////////////////////////////////////////////////////////////////
+        // ListExtractor
+        //////////////////////////////////////////////////////////////////////////*/
+
+        @Test
+        public void testRelatedItems() throws Exception {
+            defaultTestRelatedItems(extractor, YouTube.getServiceId());
+        }
+
+        @Test
+        public void testMoreRelatedItems() throws Exception {
+            defaultTestMoreItems(extractor, YouTube.getServiceId());
+        }
+
+         /*//////////////////////////////////////////////////////////////////////////
+         // ChannelExtractor
+         //////////////////////////////////////////////////////////////////////////*/
+
+        @Test
+        public void testDescription() throws Exception {
+            final String description = extractor.getDescription();
+            assertTrue(description, description.contains("Eminem on Vevo"));
+        }
+
+        @Test
+        public void testAvatarUrl() throws Exception {
+            String avatarUrl = extractor.getAvatarUrl();
+            assertIsSecureUrl(avatarUrl);
+            assertTrue(avatarUrl, avatarUrl.contains("yt3"));
+        }
+
+        @Test
+        public void testBannerUrl() throws Exception {
+            String bannerUrl = extractor.getBannerUrl();
+            assertIsSecureUrl(bannerUrl);
+            assertTrue(bannerUrl, bannerUrl.contains("yt3"));
+        }
+
+        @Test
+        public void testFeedUrl() throws Exception {
+            assertEquals("https://www.youtube.com/feeds/videos.xml?channel_id=UC20vb-R_px4CguHzzBPhoyQ", extractor.getFeedUrl());
+        }
+
+        @Test
+        public void testSubscriberCount() throws Exception {
+            // there is no "Subscribe" button
+            long subscribers = extractor.getSubscriberCount();
+            assertEquals("Wrong subscriber count", -1, subscribers);
+        }
+    }
+
+
+
     public static class RandomChannel implements BaseChannelExtractorTest {
         private static YoutubeChannelExtractor extractor;
 
@@ -483,8 +577,9 @@ public class YoutubeChannelExtractorTest {
 
         @Test
         public void testSubscriberCount() throws Exception {
-            assertTrue("Wrong subscriber count", extractor.getSubscriberCount() >= 50);
+            long subscribers = extractor.getSubscriberCount();
+            assertTrue("Wrong subscriber count: " + subscribers, subscribers >= 50);
+        }
     }
 }
-};