implemented iterator design pattern

pypatterns/behavioral/iterator.py

@@ -0,0 +1,33 @@
+from abc import ABCMeta, abstractmethod
+
+
+class Iterator(object):
+    """
+    An Iterator class for the Iterator design pattern.
+    """
+    def __init__(self, iterable):
+        """
+        Initialize a new Iterator instance.
+
+        @param iterable: An Iterable object to iterate over.
+        @type iterable: Iterable
+        """
+        self.iterable = iterable
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        return self.iterable.__next__()
+
+
+class Iterable(object, metaclass=ABCMeta):
+    """
+    An abstract class representing an Iterable object as part of the Iterator design pattern.
+    """
+    @abstractmethod
+    def __next__(self):
+        """
+        All Iterable's must implement a __next__ method which eventually raises StopIteration.
+        """
+        pass

tests/behavioral_tests/test_iterator.py

@@ -0,0 +1,109 @@
+from unittest import TestCase
+from pypatterns.behavioral.iterator import Iterable, Iterator
+
+
+class IterableTestCase(TestCase):
+    """
+    Unit testing class for the Iterable class.
+    """
+    def setUp(self):
+        """
+        Initialize testing data.
+        """
+        class Counter(Iterable):
+
+            def __init__(self, max):
+                self.count = 0
+                self.max = max
+
+            def __next__(self):
+                self.count += 1
+                if self.count > self.max:
+                    raise StopIteration
+                else:
+                    return self.count - 1
+
+        self.counter_class = Counter
+
+    def test_next(self):
+        """
+        Test the iterables next method.
+
+        @raise AssertionError: If the test fails.
+        """
+        counter = self.counter_class(10)
+        for i in range(10):
+            self.assertEquals(i, counter.__next__())
+
+    def test_stop_iteration(self):
+        """
+        Test that StopIteration is raised.
+
+        @raise AssertionError: If the test fails.
+        """
+        counter = self.counter_class(0)
+        with self.assertRaises(StopIteration):
+            counter.__next__()
+
+
+class IteratorTestCase(TestCase):
+    """
+    Unit testing class for the Iterator class.
+    """
+    def setUp(self):
+        """
+        Initialize testing data.
+        """
+        class Counter(Iterable):
+
+            def __init__(self, max):
+                self.count = 0
+                self.max = max
+
+            def __next__(self):
+                self.count += 1
+                if self.count > self.max:
+                    raise StopIteration
+                else:
+                    return self.count - 1
+
+        class CounterIterator(Iterator):
+
+            def __init__(self):
+                super().__init__(Counter(10))
+
+        self.counter_iterator_class = CounterIterator
+
+    def test_next(self):
+        """
+        Test the built in next method on the Iterator.
+
+        @raise AssertionError: If the test fails.
+        """
+        counter_iterator = self.counter_iterator_class()
+        for i in range(10):
+            self.assertEquals(i, next(counter_iterator))
+
+    def test_stop_iteration(self):
+        """
+        Test that stop iteration is raised.
+
+        @raise AssertionError: If the test fails.
+        """
+        counter_iterator = self.counter_iterator_class()
+
+        with self.assertRaises(StopIteration):
+            for i in range(12):
+                next(counter_iterator)
+
+    def test_loop(self):
+        """
+        Test looping over an Iterator class.
+
+        @raise AssertionError: If the test fails.
+        """
+        counter_iterator = self.counter_iterator_class()
+        i = 0
+        for count in counter_iterator:
+            self.assertEquals(i, count)
+            i += 1