@Test
public void testFields() {
final NullNode node = NullNode.getInstance();
assertEquals(0, node.getTreeSize());
assertNull(node.getName());
assertNull(node.getLeft());
assertNull(node.getRight());
}
@Test
public void testWalk() throws Exception {
NullNode.getInstance().walk();
Mockito.verifyZeroInteractions(getStdOutMock());
}
/** Verify if {@link NullNode#getInstance()} actually returns the same object instance */
@Test
public void testGetInstance() {
final NullNode instance = NullNode.getInstance();
assertNotNull(instance);
assertSame(instance, NullNode.getInstance());
}