adding tests for ProviderDelegate, making of some refactoring

objects/providers.py

@@ -2,7 +2,7 @@
 
 from collections import Iterable
 
-from .utils import is_provider
+from .utils import ensure_is_provider
 from .utils import is_injection
 from .utils import is_init_arg_injection
 from .utils import is_attribute_injection
@@ -32,10 +32,7 @@ class Provider(object):
 
     def override(self, provider):
         """Override provider with another provider."""
-        if not is_provider(provider):
-            raise Error('Expected provider as an overriding instance, '
-                        'got {}'.format(str(provider)))
-        self.overridden.append(provider)
+        self.overridden.append(ensure_is_provider(provider))
 
     @property
     def last_overriding(self):
@@ -58,7 +55,7 @@ class ProviderDelegate(Provider):
 
         :type delegated: Provider
         """
-        self.delegated = delegated
+        self.delegated = ensure_is_provider(delegated)
         super(ProviderDelegate, self).__init__()
 
     def __call__(self):

objects/utils.py

@@ -2,6 +2,8 @@
 
 from inspect import isclass
 
+from .errors import Error
+
 
 def is_provider(instance):
     """Check if instance is provider instance."""
@@ -9,6 +11,14 @@ def is_provider(instance):
             hasattr(instance, '__IS_OBJECTS_PROVIDER__'))
 
 
+def ensure_is_provider(instance):
+    """Check if instance is provider instance, otherwise raise and error."""
+    if not is_provider(instance):
+        raise Error('Expected provider instance, '
+                    'got {}'.format(str(instance)))
+    return instance
+
+
 def is_injection(instance):
     """Check if instance is injection instance."""
     return (not isclass(instance) and

tests/test_providers.py

@@ -24,55 +24,85 @@ class ProviderTest(unittest.TestCase):
 
     """Provider test cases."""
 
-    def test_init(self):
-        """Test creating and initialization."""
-        self.assertIsInstance(Provider(), Provider)
+    def setUp(self):
+        """Set test cases environment up."""
+        self.provider = Provider()
 
     def test_is_provider(self):
         """Test `is_provider` check."""
-        self.assertTrue(is_provider(Provider()))
+        self.assertTrue(is_provider(self.provider))
 
     def test_call(self):
         """Test call."""
-        self.assertRaises(NotImplementedError, Provider().__call__)
+        self.assertRaises(NotImplementedError, self.provider.__call__)
 
     def test_delegate(self):
         """Test creating of provider delegation."""
-        provider = Provider()
-        delegate = provider.delegate()
+        delegate1 = self.provider.delegate()
 
-        self.assertIsInstance(delegate, ProviderDelegate)
-        self.assertIs(delegate.delegated, provider)
+        self.assertIsInstance(delegate1, ProviderDelegate)
+        self.assertIs(delegate1.delegated, self.provider)
+
+        delegate2 = self.provider.delegate()
+
+        self.assertIsInstance(delegate2, ProviderDelegate)
+        self.assertIs(delegate2.delegated, self.provider)
+
+        self.assertIsNot(delegate1, delegate2)
 
     def test_override(self):
         """Test provider overriding."""
-        provider = Provider()
         overriding_provider = Provider()
-        provider.override(overriding_provider)
-        self.assertTrue(provider.overridden)
+        self.provider.override(overriding_provider)
+        self.assertTrue(self.provider.overridden)
 
     def test_override_with_not_provider(self):
         """Test provider overriding with not provider instance."""
-        self.assertRaises(Error, Provider().override, object())
+        self.assertRaises(Error, self.provider.override, object())
 
     def test_last_overriding(self):
         """Test getting last overriding provider."""
-        provider = Provider()
         overriding_provider1 = Provider()
         overriding_provider2 = Provider()
 
-        provider.override(overriding_provider1)
-        self.assertIs(provider.last_overriding, overriding_provider1)
+        self.provider.override(overriding_provider1)
+        self.assertIs(self.provider.last_overriding, overriding_provider1)
 
-        provider.override(overriding_provider2)
-        self.assertIs(provider.last_overriding, overriding_provider2)
+        self.provider.override(overriding_provider2)
+        self.assertIs(self.provider.last_overriding, overriding_provider2)
 
     def test_last_overriding_of_not_overridden_provider(self):
         """Test getting last overriding from not overridden provider."""
         try:
-            Provider().last_overriding
+            self.provider.last_overriding
         except Error:
             pass
         else:
             self.fail('Got en error in {}'.format(
                 str(self.test_last_overriding_of_not_overridden_provider)))
+
+
+class ProviderDelegateTest(unittest.TestCase):
+
+    """ProviderDelegate test cases."""
+
+    def setUp(self):
+        """Set test cases environment up."""
+        self.delegated = Provider()
+        self.delegate = ProviderDelegate(delegated=self.delegated)
+
+    def test_is_provider(self):
+        """Test `is_provider` check."""
+        self.assertTrue(is_provider(self.delegate))
+
+    def test_init_with_not_provider(self):
+        """Test that delegate accepts only another provider as delegated."""
+        self.assertRaises(Error, ProviderDelegate, delegated=object())
+
+    def test_call(self):
+        """ Test returning of delegated provider."""
+        delegated1 = self.delegate()
+        delegated2 = self.delegate()
+
+        self.assertIs(delegated1, self.delegated)
+        self.assertIs(delegated2, self.delegated)