@Test public void testAddRemoveListener() { ResourceManager resourceManagerX = new ResourceManager(); IResourceListener listener = new MockResourceListener(); Assert.assertTrue(resourceManagerX.addResourceListener(listener)); Assert.assertFalse(resourceManagerX.addResourceListener(listener)); // Add again Assert.assertTrue(resourceManagerX.removeResourceListener(listener)); Assert.assertFalse(resourceManagerX.removeResourceListener(listener)); // Add again }