Add tests for play queue items' equals()

app/src/test/java/org/schabi/newpipe/player/playqueue/PlayQueueItemTest.java

@@ -0,0 +1,19 @@
+package org.schabi.newpipe.player.playqueue;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+public class PlayQueueItemTest {
+
+    public static final String URL = "MY_URL";
+
+    @Test
+    public void equalsMustNotBeOverloaded() {
+        final PlayQueueItem a = PlayQueueTest.makeItemWithUrl(URL);
+        final PlayQueueItem b = PlayQueueTest.makeItemWithUrl(URL);
+        assertEquals(a, a);
+        assertNotEquals(a, b); // they should compare different even if they have the same data
+    }
+}

app/src/test/java/org/schabi/newpipe/player/playqueue/PlayQueueTest.java

@@ -15,6 +15,7 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.spy;
@@ -148,6 +149,15 @@ public void outOfBounds() {
             assertNull(queue.getItem(-1));
             assertNull(queue.getItem(5));
         }
+
+        @Test
+        public void itemsAreNotCloned() {
+            final PlayQueueItem item = makeItemWithUrl("A url");
+            final PlayQueue playQueue = makePlayQueue(0, Collections.singletonList(item));
+
+            // make sure that items are not cloned when added to the queue
+            assertSame(playQueue.getItem(), item);
+        }
     }
 
     public static class EqualsTests {
@@ -162,6 +172,14 @@ public void sameStreams() {
             assertEquals(queue1, queue2);
         }
 
+        @Test
+        public void sameStreamsDifferentIndex() {
+            final List<PlayQueueItem> streams = Collections.nCopies(5, item1);
+            final PlayQueue queue1 = makePlayQueue(1, streams);
+            final PlayQueue queue2 = makePlayQueue(4, streams);
+            assertEquals(queue1, queue2);
+        }
+
         @Test
         public void sameSizeDifferentItems() {
             final List<PlayQueueItem> streams1 = Collections.nCopies(5, item1);