Abstract base class for DS

pygorithm/data_structures/base.py

@@ -0,0 +1,22 @@
+
+import inspect
+
+
+class BaseDataStructure(object):
+
+    @classmethod
+    def get_code(cls):
+        """
+        returns the code for the current class
+        """
+        return inspect.getsource(cls)
+
+    @staticmethod
+    def time_complexities():
+        """
+        Prints time complexities of different operations
+        """
+        # TODO: Is it really required for all data structres?
+        # If it is, change on `raise NotImplementedError`,
+        # but for now not all classes have this method.
+        pass

pygorithm/data_structures/stack.py

@@ -3,10 +3,11 @@
 Created On: 3rd August 2017
 """
 from string import ascii_letters
-import inspect
 
+from .base import BaseDataStructure
 
-class Stack(object):
+
+class Stack(BaseDataStructure):
     """
     Stack object
     """
@@ -66,15 +67,8 @@ def size(self):
         """
         return len(self.stack)
 
-    @staticmethod
-    def get_code():
-        """
-        returns the code for current class
-        """
-        return inspect.getsource(Stack)
-
 
-class InfixToPostfix(object):
+class InfixToPostfix(BaseDataStructure):
     """InfixToPostfix
     get the postfix of the given infix expression
     """
@@ -136,10 +130,3 @@ def infix_to_postfix(self):
         while not self.my_stack.is_empty():
             postfix.append(self.my_stack.pop())
         return ' '.join(postfix)
-
-    @staticmethod
-    def get_code():
-        """
-        returns the code of the current class
-        """
-        return inspect.getsource(InfixToPostfix)

tests/test_data_structure.py

@@ -11,7 +11,31 @@
     trie)
 
 
-class TestStack(unittest.TestCase):
+class TestDSInterfaceMixin(object):
+
+    DS_Class = None
+
+    def _check_ds_class_set(self):
+        if self.DS_Class is None:
+            raise ValueError(
+                'When inherit from TestDataStructureMixin, set DS_Class class variable'
+            )
+
+    def test_get_code_method_exists(self):
+        import inspect
+
+        self._check_ds_class_set()
+        self.assertEqual(self.DS_Class.get_code(), inspect.getsource(self.DS_Class))
+
+    def test_time_complexities_method_exists(self):
+        self._check_ds_class_set()
+        self.assertTrue(hasattr(self.DS_Class, 'time_complexities'))
+
+
+class TestStack(TestDSInterfaceMixin, unittest.TestCase):
+
+    DS_Class = stack.Stack
+
     def test_stack(self):
         myStack = stack.Stack()  # create a stack with default stack size 10
         myStack.push(2)
@@ -30,7 +54,10 @@ def test_stack(self):
         self.assertTrue(nullStack.is_empty())
 
 
-class TestInfixToPostfix(unittest.TestCase):
+class TestInfixToPostfix(TestDSInterfaceMixin, unittest.TestCase):
+
+    DS_Class = stack.InfixToPostfix
+
     def test_infix_to_postfix(self):
         myExp = 'a+b*(c^d-e)^(f+g*h)-i'
         myExp = [i for i in myExp]