added test that pop last tail and added reset of pointers when removing last node

Author: Droid-An

Sprint-2/implement_linked_list/linked_list.py

@@ -31,13 +31,17 @@ def pop_tail(self):
         else:
             self.head = None
             self.tail = None
+            node.previous = None
+            node.next = None
         return node.value
 
     def remove(self, node):
         if self.head == node:
             if self.tail == node:
                 # head == node, tail == node
                 self.head = self.tail = None
+                node.previous = None
+                node.next = None
             else:
                 # head == node, tail != node
                 self.head = node.next

Sprint-2/implement_linked_list/linked_list_test.py

@@ -42,6 +42,21 @@ def test_remove_last(self):
         l.remove(a)
         l.remove(b)
         self.assertIsNone(a.next)
+        self.assertIsNone(a.previous)
+        self.assertIsNone(b.next)
+        self.assertIsNone(b.previous)
+        self.assertIsNone(l.head)
+        self.assertIsNone(l.tail)
+
+    def test_pop_last_tail(self):
+        l = LinkedList()
+        a = l.push_head("a")
+        b = l.push_head("b")
+        c = l.push_head("c")
+        l.remove(a)
+        l.remove(c)
+        l.pop_tail()
+        self.assertIsNone(b.next)
         self.assertIsNone(b.previous)
         self.assertIsNone(l.head)
         self.assertIsNone(l.tail)