Validate that the item state is only changed when needed

Follow-up to commit 8172d87477 (#3067)
that adds test coverage for the resolved issue.

Also, fix that commit by making the update condition more explicit:
the FeedItem state is only changed when a state switch is necessary.
In other words, an item marked as *new* that gets downloaded should
lose the *new* mark and gain the *unplayed* mark instead.

core/src/main/java/de/danoeh/antennapod/core/feed/FeedMedia.java

@@ -594,7 +594,7 @@ public class FeedMedia extends FeedFile implements Playable {
     @Override
     public void setDownloaded(boolean downloaded) {
         super.setDownloaded(downloaded);
-        if(item != null && downloaded && !item.isPlayed()) {
+        if(item != null && downloaded && item.isNew()) {
             item.setPlayed(false);
         }
     }

core/src/test/java/de/danoeh/antennapod/core/feed/FeedMediaMother.java

@@ -0,0 +1,13 @@
+package de.danoeh.antennapod.core.feed;
+
+class FeedMediaMother {
+
+    private static final String EPISODE_URL = "http://example.com/episode";
+    private static final long SIZE = 42;
+    private static final String MIME_TYPE = "audio/mp3";
+
+    static FeedMedia anyFeedMedia() {
+        return new FeedMedia(null, EPISODE_URL, SIZE, MIME_TYPE);
+    }
+
+}

core/src/test/java/de/danoeh/antennapod/core/feed/FeedMediaTest.java

@@ -0,0 +1,72 @@
+package de.danoeh.antennapod.core.feed;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static de.danoeh.antennapod.core.feed.FeedMediaMother.anyFeedMedia;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class FeedMediaTest {
+
+    private FeedMedia media;
+
+    @Before
+    public void setUp() {
+        media = anyFeedMedia();
+    }
+
+    /**
+     * Downloading a media from a not new and not played item should not change the item state.
+     */
+    @Test
+    public void testDownloadMediaOfNotNewAndNotPlayedItem_unchangedItemState() {
+        FeedItem item = mock(FeedItem.class);
+        when(item.isNew()).thenReturn(false);
+        when(item.isPlayed()).thenReturn(false);
+
+        media.setItem(item);
+        media.setDownloaded(true);
+
+        verify(item, never()).setNew();
+        verify(item, never()).setPlayed(true);
+        verify(item, never()).setPlayed(false);
+    }
+
+    /**
+     * Downloading a media from a played item (thus not new) should not change the item state.
+     */
+    @Test
+    public void testDownloadMediaOfPlayedItem_unchangedItemState() {
+        FeedItem item = mock(FeedItem.class);
+        when(item.isNew()).thenReturn(false);
+        when(item.isPlayed()).thenReturn(true);
+
+        media.setItem(item);
+        media.setDownloaded(true);
+
+        verify(item, never()).setNew();
+        verify(item, never()).setPlayed(true);
+        verify(item, never()).setPlayed(false);
+    }
+
+    /**
+     * Downloading a media from a new item (thus not played) should change the item to not played.
+     */
+    @Test
+    public void testDownloadMediaOfNewItem_changedToNotPlayedItem() {
+        FeedItem item = mock(FeedItem.class);
+        when(item.isNew()).thenReturn(true);
+        when(item.isPlayed()).thenReturn(false);
+
+        media.setItem(item);
+        media.setDownloaded(true);
+
+        verify(item).setPlayed(false);
+        verify(item, never()).setNew();
+        verify(item, never()).setPlayed(true);
+    }
+
+}