added new test and slightly refactored the logic of removing the head

Author: Droid-An

Sprint-2/implement_linked_list/linked_list.py

@@ -1,3 +1,10 @@
+class Node:
+    def __init__(self, value):
+        self.value = value
+        self.previous = None
+        self.next = None
+
+
 class LinkedList:
     def __init__(self):
         self.head = None
@@ -34,7 +41,7 @@ def remove(self, node):
             else:
                 # head == node, tail != node
                 self.head = node.next
-                node.next.previous = node.previous = node.next = None
+                self.head.previous = node.next = None
         else:
             if self.tail == node:
                 # head != node, tail == node
@@ -45,10 +52,3 @@ def remove(self, node):
                 node.previous.next = node.next
                 node.next.previous = node.previous
                 node.previous = node.next = None
-
-
-class Node:
-    def __init__(self, value):
-        self.value = value
-        self.previous = None
-        self.next = None

Sprint-2/implement_linked_list/linked_list_test.py

@@ -2,6 +2,7 @@
 
 from linked_list import LinkedList
 
+
 class LinkedListTest(unittest.TestCase):
     def test_pushes_then_pops(self):
         l = LinkedList()
@@ -34,6 +35,17 @@ def test_remove_tail(self):
         self.assertIsNone(b.next)
         self.assertIsNone(b.previous)
 
+    def test_remove_last(self):
+        l = LinkedList()
+        a = l.push_head("a")
+        b = l.push_head("b")
+        l.remove(a)
+        l.remove(b)
+        self.assertIsNone(a.next)
+        self.assertIsNone(b.previous)
+        self.assertIsNone(l.head)
+        self.assertIsNone(l.tail)
+
 
 if __name__ == "__main__":
     unittest.main()