Linked list

linked_list.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+from __future__ import unicode_literals
 
 
 class Node(object):
@@ -7,32 +8,33 @@ def __init__(self, data, nextNode=None):
         self.nextNode = nextNode
 
     def __str__(self):
-        return self.data
+        return str(self.data)
 
     def __repr__(self):
-        return self.data
+        return repr(self.data)
 
 
 class LinkedList(object):
     def __init__(self, firstNode=None):
         self.firstNode = firstNode
 
-    def insert(self, newNode):
-        # insert newNode at beginning of list
+    def insert(self, val):
+        # insert val at beginning of list
+        self.newNode = Node(val)
         if not self.firstNode:
-            self.firstNode = newNode
+            self.firstNode = self.newNode
         else:
-            newNode.nextNode = self.firstNode
-            self.firstNode = newNode
+            self.newNode.nextNode = self.firstNode
+            self.firstNode = self.newNode
 
     def pop(self):
         # pops first value from list and returns it
         if self.size() == 0:
-            return "THE LIST! IT'S EMPTY!!"
+            raise ValueError("The list is empty")
         else:
             obsoleteNode = self.firstNode
             self.firstNode = self.firstNode.nextNode
-            return obsoleteNode.data
+            return obsoleteNode.data.encode('utf-8')
 
     def size(self):
         # returns length of list
@@ -46,6 +48,8 @@ def size(self):
     def search(self, val):
         # return node containing 'val' in list, if present (else None)
         currentNode = self.firstNode
+        if currentNode.data is None:
+            raise ValueError()
         while currentNode.data != val:
             if currentNode.nextNode is None:
                 return None
@@ -56,15 +60,12 @@ def search(self, val):
     def remove(self, node):
         # remove node from list, wherever it might be
         if self.size() == 0:
-            return "THE LIST! IT'S EMPTY!!"
+            raise ValueError("The list is empty")
         else:
             prevNode = None
             currentNode = self.firstNode
-            foundNode = False
-            while not foundNode:
-                if currentNode == node:
-                    foundNode = True
-                elif currentNode is None:
+            while currentNode is not node:
+                if currentNode is None:
                     raise ValueError()
                 else:
                     prevNode = currentNode
@@ -80,6 +81,6 @@ def display(self):
         display = "("
         currentNode = self.firstNode
         while currentNode is not None:
-            display += currentNode.data + ", "
+            display += currentNode.data.encode('utf-8') + ", "
             currentNode = currentNode.nextNode
         return display + ")"

test_linked_list.py

@@ -3,105 +3,84 @@
 import pytest
 
 
-def test_node_data():
-    newNode = Node("Bob")
-    assert newNode.data == "Bob"
-
-
 def test_node_add():
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
+    newList.insert("Bob")
     assert newList.firstNode.data == "Bob"
 
 
 def test_next_node_none():
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
+    newList.insert("Bob")
     assert newList.firstNode.nextNode is None
 
 
 def test_add_second_node():
-    joe = Node("Joe")
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
-    newList.insert(joe)
+    newList.insert("Bob")
+    newList.insert("Joe")
     assert newList.firstNode.nextNode.data == "Bob"
 
 
 def test_pop():
-    joe = Node("Joe")
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
-    newList.insert(joe)
+    newList.insert("Bob")
+    newList.insert("Joe")
     assert newList.pop() == "Joe"
 
 
 def test_pop_size():
-    joe = Node("Joe")
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
-    newList.insert(joe)
+    newList.insert("Bob")
+    newList.insert("Joe")
     newList.pop()
     assert newList.size() == 1
 
 
 def test_size():
-    joe = Node("Joe")
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
-    newList.insert(joe)
+    newList.insert("Bob")
+    newList.insert("Joe")
     assert newList.size() == 2
 
 
 def test_search_fail():
-    joe = Node("Joe")
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
-    newList.insert(joe)
+    newList.insert("Bob")
+    newList.insert("Joe")
     assert newList.search("Fred") is None
 
 
 def test_search_success():
-    joe = Node("Joe")
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
-    newList.insert(joe)
-    assert newList.search("Bob") == bob
+    newList.insert("Bob")
+    newList.insert("Joe")
+    assert newList.search("Bob") is not None
 
 
 def test_remove():
-    joe = Node("Joe")
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
-    newList.insert(joe)
-    newList.remove(bob)
+    newList.insert("Bob")
+    newList.insert("Joe")
+    newList.remove(newList.search("Bob"))
     assert newList.search("Bob") is None
 
 
 def test_remove_empty():
     newList = LinkedList()
-    assert newList.remove("Bob") == "THE LIST! IT'S EMPTY!!"
+    with pytest.raises(ValueError):
+        newList.remove("Bob")
 
 
 def test_pop_empty():
     newList = LinkedList()
-    assert newList.pop() == "THE LIST! IT'S EMPTY!!"
+    with pytest.raises(ValueError):
+        newList.pop()
 
 
 def test_remove_fail():
-    joe = Node("Joe")
-    bob = Node("Bob")
     newList = LinkedList()
-    newList.insert(bob)
-    newList.insert(joe)
+    newList.insert("Bob")
+    newList.insert("Joe")
     with pytest.raises(ValueError):
         newList.remove("Fred")