@Test
public void testDeleteDoubleNode() throws Exception {
DoubleNode<String> node = new DoubleNode<>("First");
node.appendToTail("Second");
node.appendToTail("Third");
DoubleNode<String> newDoubleNode = node.deleteNode("Second");
assertEquals("First", newDoubleNode.getData());
assertEquals("Third", newDoubleNode.getNext().getData());
}
@Test
public void testAppendToTail() throws Exception {
DoubleNode<String> node = new DoubleNode<>("First");
node.appendToTail("Second");
assertEquals("First", node.getData());
assertEquals("Second", node.getNext().getData());
assertEquals("First", node.getNext().getPrevious().getData());
}
@Test
public void testDeletingNonExistingItem() throws Exception {
DoubleNode<String> node = new DoubleNode<>("First");
node.appendToTail("Second");
DoubleNode<String> newDoubleNode = node.deleteNode("Non-existing-item");
assertEquals("First", newDoubleNode.getData());
assertEquals("Second", newDoubleNode.getNext().getData());
}
@Test
public void testDeleteAllDoubleNodes() throws Exception {
DoubleNode<String> node = new DoubleNode<>("First");
node.appendToTail("Second");
DoubleNode<String> nodeWithOneElement = node.deleteNode("First");
DoubleNode<String> nodeWithoutElements = nodeWithOneElement.deleteNode("Second");
assertTrue(nodeWithoutElements == null);
}