Switched to Mockito rather than manually written mock class.

pom.xml

@@ -115,6 +115,12 @@
             <version>4.12</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>2.6.5</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>com.1stleg</groupId>
             <artifactId>jnativehook</artifactId>

src/test/java/musicplayer/db/HibernateDatabaseTest.java

@@ -7,6 +7,11 @@ import org.jaudiotagger.tag.Tag;
 import org.jaudiotagger.tag.id3.ID3v23Tag;
 import org.junit.Before;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+import static org.mockito.Mockito.*;
 
 import java.io.File;
 import java.nio.file.Path;
@@ -17,10 +22,14 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+@RunWith(MockitoJUnitRunner.class)
 public class HibernateDatabaseTest {
 
     private IDatabase database;
 
+    @Mock
+    ILibrary library;
+
     @Before
     public void setUp(){
         database = new HibernateDatabase(true);
@@ -222,41 +231,8 @@ public class HibernateDatabaseTest {
         Path dir = new File(HibernateDatabaseTest.class.getResource("/sample.mp3").getFile()).getParentFile().toPath();
         List<Path> dirList = new ArrayList<>();
         dirList.add(dir);
-        FakeLibrary library = new FakeLibrary(database);
         database.processSongsWithCallback(library, dirList);
         assertEquals(1, database.listAllT(Song.class).get().size());
-        assertTrue(library.success);
-        assertFalse(library.failed);
-    }
-
-    private class FakeLibrary extends ILibrary{
-
-        public boolean success = false;
-        public boolean failed = false;
-
-        public FakeLibrary(IDatabase database) {
-            super(database);
-        }
-
-        @Override
-        public void showSongs() {}
-
-        @Override
-        public <T extends HasSongs & Comparable<T>> void showGroupedSongs(Class<T> grouping) {}
-
-        @Override
-        public void updateLibrary() {}
-
-        @Override
-        public void refreshLibrary() {}
-
-        @Override
-        public void libraryUpdateFailed(String message) { failed = true;}
-
-        @Override
-        public void libraryUpdated() { success = true;}
-
-        @Override
-        public void currentlyUpdating(String name) {}
+        verify(library).libraryUpdated();
     }
 }