implemented chain of responsibility pattern.

tests/behavioral_tests/test_chain.py

@@ -0,0 +1,140 @@
+from unittest import TestCase
+from pypatterns.behavioral.chain import ChainException, ChainLink, Chain
+
+
+class ChainLinkTestCase(TestCase):
+    """
+    Unit testing class for the ChainLink class.
+    """
+    def setUp(self):
+        """
+        Initialize testing data.
+        """
+        class ConcreteChainLinkThree(ChainLink):
+
+            def handle(self, request):
+                if request == 'handle_three':
+                    return "Handled in chain link three"
+                else:
+                    return self.successor_handle(request)
+
+        class ConcreteChainLinkTwo(ChainLink):
+
+            def __init__(self):
+                super().__init__()
+                self.set_successor(ConcreteChainLinkThree())
+
+            def handle(self, request):
+                if request == 'handle_two':
+                    return "Handled in chain link two"
+                else:
+                    return self.successor_handle(request)
+
+        class ConcreteChainLinkOne(ChainLink):
+
+            def __init__(self):
+                super().__init__()
+                self.set_successor(ConcreteChainLinkTwo())
+
+            def handle(self, request):
+                if request == 'handle_one':
+                    return "Handled in chain link one"
+                else:
+                    return self.successor_handle(request)
+
+        self.chain_link_one_class = ConcreteChainLinkOne
+
+    def test_success_handle(self):
+        """
+        Test the handle method with successful requests.
+
+        @raise AssertionError: If the test fails.
+        """
+        handler = self.chain_link_one_class()
+
+        self.assertEquals("Handled in chain link one", handler.handle("handle_one"))
+        self.assertEquals("Handled in chain link two", handler.handle("handle_two"))
+        self.assertEquals("Handled in chain link three", handler.handle("handle_three"))
+
+    def test_fail_handle(self):
+        """
+        Test the handle method with unsuccessful requests.
+
+        @raise AssertionError: If the test fails.
+        """
+        handler = self.chain_link_one_class()
+        with self.assertRaises(ChainException):
+            handler.handle("foo")
+
+
+class ChainTestCase(TestCase):
+    """
+    Unit testing class for the Chain class.
+    """
+    def setUp(self):
+        """
+        Initialize testing data.
+        """
+        class ConcreteChainLinkThree(ChainLink):
+
+            def handle(self, request):
+                if request == 'handle_three':
+                    return "Handled in chain link three"
+                else:
+                    return self.successor_handle(request)
+
+        class ConcreteChainLinkTwo(ChainLink):
+
+            def __init__(self):
+                super().__init__()
+                self.set_successor(ConcreteChainLinkThree())
+
+            def handle(self, request):
+                if request == 'handle_two':
+                    return "Handled in chain link two"
+                else:
+                    return self.successor_handle(request)
+
+        class ConcreteChainLinkOne(ChainLink):
+
+            def __init__(self):
+                super().__init__()
+                self.set_successor(ConcreteChainLinkTwo())
+
+            def handle(self, request):
+                if request == 'handle_one':
+                    return "Handled in chain link one"
+                else:
+                    return self.successor_handle(request)
+
+        class ConcreteChain(Chain):
+
+            def __init__(self):
+                super().__init__(ConcreteChainLinkOne())
+
+            def fail(self):
+                return 'Fail'
+
+        self.chain_class = ConcreteChain
+
+    def test_success_handle(self):
+        """
+        Test the handle method with a successful request
+
+        @raise AssertionError: If the test fails.
+        """
+        chain = self.chain_class()
+
+        self.assertEquals("Handled in chain link one", chain.handle("handle_one"))
+        self.assertEquals("Handled in chain link two", chain.handle("handle_two"))
+        self.assertEquals("Handled in chain link three", chain.handle("handle_three"))
+
+    def test_fail_handle(self):
+        """
+        Test the handle method with unsuccessful requests.
+
+        @raise AssertionError: If the test fails.
+        """
+        chain = self.chain_class()
+
+        self.assertEquals("Fail", chain.handle("foo"))