def test_shift():
dList = Double_list()
dList.insert("Harry")
dList.insert("Ron")
dList.append("Snape")
assert dList.shift() == "Snape"
assert dList.list_ptr.node_next.node_next is None
def test_remove():
dList = Double_list()
dList.insert("Harry")
dList.insert("Ron")
dList.append("Snape")
dList.remove("Harry")
assert dList.list_ptr.node_next.node_name == "Snape"
assert dList.list_ptr.node_next.node_prev.node_name == "Ron"
def test_pop():
dList = Double_list()
dList.insert("Harry")
dList.insert("Ron")
dList.append("Snape")
assert dList.pop() == "Ron"
assert dList.list_ptr.node_name == "Harry"
assert dList.list_ptr.node_prev is None
assert dList.list_ptr.node_next.node_name == "Snape"
def test_append():
dList = Double_list()
dList.insert("Harry")
dList.insert("Ron")
dList.append("Snape")
assert dList.list_ptr.node_next.node_name == "Harry"
middle_node = dList.list_ptr.node_next
assert middle_node.node_next.node_name == "Snape"
assert middle_node.node_next.node_next is None
assert middle_node.node_next.node_prev.node_name == "Harry"
