Add tests for providers.Config & refactoring of it

objects/providers.py

@@ -303,23 +303,27 @@ class Config(Provider):
 
     def __getattr__(self, item):
         """Return instance of deferred config."""
-        return _DeferredConfig(parents=(item,),
+        return _ChildConfig(parents=(item,), root_config=self)
-                               root_config=self)
 
     def __call__(self, paths=None):
         """Return provided instance."""
         value = self.value
         if paths:
             for path in paths:
-                value = value[path]
+                try:
-            return value
+                    value = value[path]
+                except KeyError:
+                    raise Error('Config key '
+                                '"{}" is undefined'.format('.'.join(paths)))
+        return value
 
 
-class _DeferredConfig(Provider):
+class _ChildConfig(Provider):
 
-    """Deferred config provider.
+    """Child config provider.
 
-    Deferred config providers provide an value from the root config object.
+    Child config provide an value from the root config object according to
+    the current path in the config tree.
     """
 
     __slots__ = ('parents', 'root_config')
@@ -328,12 +332,12 @@ class _DeferredConfig(Provider):
         """Initializer."""
         self.parents = parents
         self.root_config = root_config
-        super(_DeferredConfig, self).__init__()
+        super(_ChildConfig, self).__init__()
 
     def __getattr__(self, item):
         """Return instance of deferred config."""
-        return _DeferredConfig(parents=self.parents + (item,),
+        return _ChildConfig(parents=self.parents + (item,),
-                               root_config=self.root_config)
+                            root_config=self.root_config)
 
     def __call__(self, *args, **kwargs):
         """Return provided instance."""

tests/test_providers.py

@@ -480,7 +480,7 @@ class CallableTests(unittest.TestCase):
 
     def test_is_provider(self):
         """Test `is_provider` check."""
-        self.assertTrue(is_provider(Callable(map)))
+        self.assertTrue(is_provider(self.provider))
 
     def test_call(self):
         """Test provider call."""
@@ -517,4 +517,59 @@ class ConfigTests(unittest.TestCase):
 
     def setUp(self):
         """Set test cases environment up."""
+        self.initial_data = dict(key='value',
+                                 category=dict(setting='setting_value'))
+        self.provider = Config(self.initial_data)
+
+    def test_is_provider(self):
+        """Test `is_provider` check."""
+        self.assertTrue(is_provider(self.provider))
+
+    def test_init_without_initial_value(self):
+        """Test provider's creation with no initial value."""
+        self.assertEqual(Config()(), dict())
+
+    def test_call(self):
+        """Test returning of config value."""
+        self.assertEqual(self.provider(), self.initial_data)
+
+    def test_update_from(self):
+        """Test update of config value."""
+        self.assertEqual(self.provider(), self.initial_data)
+
+        self.initial_data['key'] = 'other_value'
+        self.provider.update_from(self.initial_data)
+        self.assertEqual(self.provider(), self.initial_data)
+
+    def test_call_child(self):
+        """Test returning of child config values."""
+        category = self.provider.category
+        category_setting = self.provider.category.setting
+
+        self.assertTrue(is_provider(category))
+        self.assertTrue(is_provider(category_setting))
+
+        self.assertEqual(category(), self.initial_data['category'])
+        self.assertEqual(category_setting(),
+                         self.initial_data['category']['setting'])
+
+    def test_call_deferred_child_and_update_from(self):
+        """Test returning of deferred child config values."""
         self.provider = Config()
+        category = self.provider.category
+        category_setting = self.provider.category.setting
+
+        self.assertTrue(is_provider(category))
+        self.assertTrue(is_provider(category_setting))
+
+        self.provider.update_from(self.initial_data)
+
+        self.assertEqual(category(), self.initial_data['category'])
+        self.assertEqual(category_setting(),
+                         self.initial_data['category']['setting'])
+
+    def test_call_deferred_child_with_empty_value(self):
+        """Test returning of deferred child config values."""
+        self.provider = Config()
+        category_setting = self.provider.category.setting
+        self.assertRaises(Error, category_setting)