add testing for null stack

dstark85 · dstark85 · commit bc2caa1d3aef · 2017-08-09T10:27:33.000-07:00
diff --git a/tests/test_data_structure.py b/tests/test_data_structure.py
@@ -17,6 +17,12 @@ def test_stack(self):
         self.assertEqual(myStack.peek(), 12)
         self.assertFalse(myStack.isEmpty())
 
+        nullStack = stack.Stack() 
+
+        self.assertEqual(nullStack.pop(), -1)
+        self.assertEqual(nullStack.peek(), -1)
+        self.assertTrue(nullStack.isEmpty())
+
 class TestInfixToPostfix(unittest.TestCase):
     def test_infix_to_postfix(self):
         myExp = 'a+b*(c^d-e)^(f+g*h)-i'
