in have written the pop and push methods but when i run the testing it still fai

Question

 in have written the pop and push methods but when i run the testing it still fails can you please help me fix it. the program has to pass the tests.  from __future__ import print_function import unittest  ''' when run with "-m unittest", the following produces:     FAILED (failures=9, errors=2)     your task is to fix the failing tests by implementing the necessary     methods. '''   class LinkedList(object):     class Node(object):         # pylint: disable=too-few-public-methods         ''' no need for get or set, we only access the values inside the             LinkedList class. and really: never have setters. '''          def __init__(self, value, next_node):             self.value = value             self.next_node = next_node      def __init__(self, initial=None):         self.front = self.back = self.current = None      def empty(self):         if self.front is None:             return True         else:             return False      def __iter__(self):         self.current = self.front         return self      def __next__(self):         if self.current:             tmp = self.current.value             self.current = self.current.next_node             return tmp         else:             raise StopIteration()      def push_front(self, value):         new = self.Node(value, self.front)         if self.empty():             self.front = self.back = new         else:             self.front = new      ''' you need to(at least) implement the following three methods'''      def pop_front(self):         tmp = self.front         if self.front is None:             return None         if self.front == self.back:             self.front = self.back = None             return         else:             self.back = None         return tmp      def push_back(self, value):         new = self.Node(value, self.front)         if self.empty():             return None         if self.front is None:             self.front = self.next_node             return         else:             self.back = new             return             # new node is the last one ^      def pop_back(self):         if self.empty():             return None         tmp = self.back.value         if not self.front.next_node:             self.front = self.back = None         else:             temp2 = self.front             while temp2.next_node is not self.back:   #traverse                 temp2 = temp2.next_node             temp2.next_node = None             self.back = temp2         return tmp      def delete(self, value):         self.current = self.back         prev = None         if self.front is None:             return None         while self.current:             if self.current.getValue() == value:                 if prev:                     prev = self.current.next_node                 else:                     self.back = self.current                 return True             else:                 prev = self.current                 self.current = self.current.next_node         return False      def find(self, value):         self.current = self.front         while self.current:             if self.current.getValue() == value:                 return value             else:                 self.current = self.current.next_node         return None   ''' C-level work '''   class TestEmpty(unittest.TestCase):     def test(self):         self.assertTrue(LinkedList().empty())   class TestDeleteFind(unittest.TestCase):     def test(self):         linked_list = LinkedList()         linked_list.find(1)         linked_list.find("foo")         linked_list.find([3, 2, 1])         self.assertEqual(linked_list.delete, ([3, 2, 1]))         self.assertEqual(linked_list.delete, "foo")         self.assertEqual(linked_list.delete, 1)         self.assertTrue(linked_list.empty())   class TestPushBackPopBack(unittest.TestCase):     def test(self):         linked_list = LinkedList()         linked_list.push_back(1)         linked_list.push_back("foo")         linked_list.push_back([3, 2, 1])         self.assertFalse(linked_list.empty())         self.assertEqual(linked_list.pop_back(), [3, 2, 1])         self.assertEqual(linked_list.pop_back(), "foo")         self.assertEqual(linked_list.pop_back(), 1)         self.assertTrue(linked_list.empty())   class TestPushFrontPopBack(unittest.TestCase):     def test(self):         linked_list = LinkedList()         linked_list.push_front(1)         linked_list.push_front(2)         linked_list.push_front(3)         self.assertFalse(linked_list.empty())         self.assertEqual(linked_list.pop_back(), 1)         self.assertEqual(linked_list.pop_back(), 2)         self.assertEqual(linked_list.pop_back(), 3)         self.assertTrue(linked_list.empty())   class TestPushFrontPopFront(unittest.TestCase):     def test(self):         linked_list = LinkedList()         linked_list.push_front(1)         linked_list.push_front(2)         linked_list.push_front(3)         self.assertEqual(linked_list.pop_front(), 3)         self.assertEqual(linked_list.pop_front(), 2)         self.assertEqual(linked_list.pop_front(), 1)         self.assertTrue(linked_list.empty())   class TestPushBackPopFront(unittest.TestCase):     def test(self):         linked_list = LinkedList()         linked_list.push_back(1)         linked_list.push_back(2)         linked_list.push_back(3)         self.assertFalse(linked_list.empty())         self.assertEqual(linked_list.pop_front(), 1)         self.assertEqual(linked_list.pop_front(), 2)         self.assertEqual(linked_list.pop_front(), 3)         self.assertTrue(linked_list.empty())   ''' B-level work '''   class TestInitialization(unittest.TestCase):     def test(self):         linked_list = LinkedList(("one", 2, 3.141592))         self.assertEqual(linked_list.pop_back(), "one")         self.assertEqual(linked_list.pop_back(), "2")         self.assertEqual(linked_list.pop_back(), "3.141592")   class TestStr(unittest.TestCase):     def test(self):         linked_list = LinkedList((1, 2, 3))         self.assertEqual(linked_list.__str__(), '1, 2, 3')   ''' A-level work '''   class TestRepr(unittest.TestCase):     def test(self):         linked_list = LinkedList((1, 2, 3))         self.assertEqual(linked_list.__repr__(), 'LinkedList((1, 2, 3))')   class TestErrors(unittest.TestCase):     def test_pop_front_empty(self):         self.assertRaises(RuntimeError, lambda: LinkedList().pop_front())      def test_pop_back_empty(self):         self.assertRaises(RuntimeError, lambda: LinkedList().pop_back())      def test_push_front_empty(self):         self.assertRaises(RuntimeError, lambda: LinkedList().push_front)      def test_push_back_empty(self):         self.assertRaises(RuntimeError, lambda: LinkedList().push_back)      def test_delete_empty(self):         self.assertRaises(RuntimeError, lambda: LinkedList().delete)      def test_Find_empty(self):         self.assertRaises(RuntimeError, lambda: LinkedList().find)   ''' write some more test cases. '''  ''' extra credit.     - write test cases for and implement a delete(value) method.     - write test cases for and implement a method that finds the middle       element with only a single traversal. '''  ''' the following is a demonstration that uses our data structure as a     stack'''   def fact(number):     '''"Pretend" to do recursion via a stack and iteration'''      if number < 0:         raise ValueError("Less than zero")     if number == 0 or number == 1:         return 1      stack = LinkedList()     while number > 1:         stack.push_front(number)         number -= 1      result = 1     while not stack.empty():         result *= stack.pop_front()      return result   class TestFactorial(unittest.TestCase):     def test_less_than_zero(self):         self.assertRaises(ValueError, lambda: fact(-1))      def test_zero(self):         self.assertEqual(fact(0), 1)      def test_one(self):         self.assertEqual(fact(1), 1)      def test_two(self):         self.assertEqual(fact(2), 2)      def test_10(self):         self.assertEqual(fact(10), 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1)   if '__main__' == __name__:     unittest.main()

Explanation / Answer

the above code should run fine.. please let me know if your face any errors.

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