Added tests for JTreeLibrary display mode functions.

src/main/java/musicplayer/library/JTreeLibrary.java

@@ -30,10 +30,10 @@ public class JTreeLibrary extends JPanel implements ILibrary, LibraryCallbackInt
 
     private IDatabase database;
     private IPlaylist playlist;
-    private static final DefaultMutableTreeNode updatingNode = new DefaultMutableTreeNode();
+    static final DefaultMutableTreeNode updatingNode = new DefaultMutableTreeNode();
     private final AtomicBoolean libraryUpdating = new AtomicBoolean(false);
     private final JComboBox<String> libraryDisplayType = new JComboBox<>();
-    private final JTree libraryTree = new JTree();
+    final JTree libraryTree = new JTree();
     private final Map<String, Runnable> libraryDisplayVariants = createDisplayVariantMap();
 
     /**

src/test/java/musicplayer/library/JTreeLibraryTest.java

@@ -0,0 +1,90 @@
+package musicplayer.library;
+
+import musicplayer.db.HibernateDatabase;
+import musicplayer.db.IDatabase;
+import musicplayer.model.Album;
+import musicplayer.model.Artist;
+import musicplayer.model.Song;
+import musicplayer.playlist.IPlaylist;
+import musicplayer.playlist.JTablePlaylist;
+import org.junit.Before;
+import org.junit.Test;
+
+import javax.swing.tree.DefaultMutableTreeNode;
+import java.io.File;
+
+import static org.junit.Assert.*;
+
+public class JTreeLibraryTest {
+
+    JTreeLibrary library;
+    Song sampleSong = new Song(ILibrary.autoParse(
+            new File(JTreeLibraryTest.class.getResource("/sample.mp3").getFile()).toPath()).get());
+    IDatabase database;
+
+    @Before
+    public void setUp() throws Exception {
+        database = new HibernateDatabase(true);
+        IPlaylist playlist = new JTablePlaylist();
+        library = new JTreeLibrary(database, playlist);
+    }
+
+    @Test
+    public void testShowSongsEmpty() throws Exception {
+        library.showSongs();
+        DefaultMutableTreeNode root = (DefaultMutableTreeNode)library.libraryTree.getModel().getRoot();
+        assertEquals(1, root.getChildCount());
+        // If empty, tree will only have a string with an error message in
+        assertEquals(String.class, ((DefaultMutableTreeNode)root.getFirstChild()).getUserObject().getClass());
+    }
+
+    @Test
+    public void testShowSongs() throws Exception {
+        database.addSong(sampleSong);
+        library.showSongs();
+        DefaultMutableTreeNode root = (DefaultMutableTreeNode)library.libraryTree.getModel().getRoot();
+        assertEquals(1, root.getChildCount());
+        assertEquals(sampleSong, ((DefaultMutableTreeNode)root.getFirstChild()).getUserObject());
+    }
+
+
+    @Test
+    public void testShowGroupedSongsEmpty() throws Exception {
+        library.showGroupedSongs(Artist.class);
+        DefaultMutableTreeNode root = (DefaultMutableTreeNode)library.libraryTree.getModel().getRoot();
+        assertEquals(1, root.getChildCount());
+        // If empty, tree will only have a string with an error message in
+        assertEquals(String.class, ((DefaultMutableTreeNode)root.getFirstChild()).getUserObject().getClass());
+    }
+
+    @Test
+    public void testShowGroupedSongsArtist() throws Exception {
+        database.addSong(sampleSong);
+        library.showGroupedSongs(Artist.class);
+        DefaultMutableTreeNode root = (DefaultMutableTreeNode)library.libraryTree.getModel().getRoot();
+        assertEquals(1, root.getChildCount());
+        DefaultMutableTreeNode artistNode = (DefaultMutableTreeNode)root.getFirstChild();
+        assertEquals(1, artistNode.getChildCount());
+        assertEquals(sampleSong.getArtist(), artistNode.getUserObject());
+        assertEquals(sampleSong, ((DefaultMutableTreeNode)artistNode.getFirstChild()).getUserObject());
+    }
+
+    @Test
+    public void testShowGroupedSongsAlbum() throws Exception {
+        database.addSong(sampleSong);
+        library.showGroupedSongs(Album.class);
+        DefaultMutableTreeNode root = (DefaultMutableTreeNode)library.libraryTree.getModel().getRoot();
+        assertEquals(1, root.getChildCount());
+        DefaultMutableTreeNode albumNode = (DefaultMutableTreeNode)root.getFirstChild();
+        assertEquals(1, albumNode.getChildCount());
+        assertEquals(sampleSong.getAlbum(), albumNode.getUserObject());
+        assertEquals(sampleSong, ((DefaultMutableTreeNode)albumNode.getFirstChild()).getUserObject());
+    }
+
+    @Test
+    public void testCurrentlyUpdating() throws Exception {
+        String updateText = "Test String";
+        library.currentlyUpdating("Test String");
+        assertEquals(updateText, library.updatingNode.getUserObject());
+    }
+}