Add validation for catalog providers type

dependency_injector/catalogs.py

@@ -166,8 +166,18 @@ class DynamicCatalog(object):
 
         :type: tuple[
             :py:class:`DeclarativeCatalog` | :py:class:`DynamicCatalog`]
+
+    .. py:attribute:: provider_type
+
+        If provider type is defined, :py:class:`DynamicCatalog` checks that
+        all of its providers are instances of
+        :py:attr:`DynamicCatalog.provider_type`.
+
+        :type: type | None
     """
 
+    provider_type = None
+
     __IS_CATALOG__ = True
     __slots__ = ('name', 'providers', 'provider_names', 'overridden_by',
                  'Bundle')
@@ -324,6 +334,11 @@ class DynamicCatalog(object):
         """
         provider = ensure_is_provider(provider)
 
+        if (self.__class__.provider_type and
+                not isinstance(provider, self.__class__.provider_type)):
+            raise Error('{0} can contaon only {1} instances'.format(
+                self.name, self.__class__.provider_type))
+
         if name in self.providers:
             raise Error('Catalog {0} already has provider with '
                         'such name - {1}'.format(self, name))
@@ -443,7 +458,13 @@ class DeclarativeCatalogMetaClass(type):
 
         cls = type.__new__(mcs, class_name, bases, attributes)
 
-        cls._catalog = DynamicCatalog()
+        if cls.provider_type:
+            cls._catalog = type('DynamicCatalog',
+                                (DynamicCatalog,),
+                                dict(provider_type=cls.provider_type))()
+        else:
+            cls._catalog = DynamicCatalog()
+
         cls._catalog.name = '.'.join((cls.__module__, cls.__name__))
         cls._catalog.bind_providers(dict(providers))
 
@@ -625,6 +646,14 @@ class DeclarativeCatalog(object):
 
         :type: :py:class:`DeclarativeCatalog` | :py:class:`DynamicCatalog` |
                None
+
+    .. py:attribute:: provider_type
+
+        If provider type is defined, :py:class:`DeclarativeCatalog` checks that
+        all of its providers are instances of
+        :py:attr:`DeclarativeCatalog.provider_type`.
+
+        :type: type | None
     """
 
     Bundle = CatalogBundle
@@ -639,6 +668,8 @@ class DeclarativeCatalog(object):
     is_overridden = bool
     last_overriding = None
 
+    provider_type = None
+
     _catalog = DynamicCatalog
 
     __IS_CATALOG__ = True

tests/test_catalogs.py

@@ -131,6 +131,51 @@ class DynamicCatalogTests(unittest.TestCase):
         self.assertIs(self.catalog.py, py)
         self.assertIs(self.catalog.get_provider('py'), py)
 
+    def test_bind_provider_with_valid_provided_type(self):
+        """Test setting of provider with provider type restriction."""
+        class SomeProvider(providers.Provider):
+            """Some provider."""
+
+        class SomeCatalog(catalogs.DynamicCatalog):
+            """Some catalog with provider type restriction."""
+
+            provider_type = SomeProvider
+
+        px = SomeProvider()
+        py = SomeProvider()
+        catalog = SomeCatalog()
+
+        catalog.bind_provider('px', px)
+        catalog.py = py
+
+        self.assertIs(catalog.px, px)
+        self.assertIs(catalog.get_provider('px'), px)
+
+        self.assertIs(catalog.py, py)
+        self.assertIs(catalog.get_provider('py'), py)
+
+    def test_bind_provider_with_invalid_provided_type(self):
+        """Test setting of provider with provider type restriction."""
+        class SomeProvider(providers.Provider):
+            """Some provider."""
+
+        class SomeCatalog(catalogs.DynamicCatalog):
+            """Some catalog with provider type restriction."""
+
+            provider_type = SomeProvider
+
+        px = providers.Provider()
+        catalog = SomeCatalog()
+
+        with self.assertRaises(errors.Error):
+            catalog.bind_provider('px', px)
+
+        with self.assertRaises(errors.Error):
+            catalog.px = px
+
+        with self.assertRaises(errors.Error):
+            catalog.bind_providers(dict(px=px))
+
     def test_bind_providers(self):
         """Test setting of provider via bind_providers() to catalog."""
         px = providers.Provider()
@@ -289,6 +334,49 @@ class DeclarativeCatalogTests(unittest.TestCase):
         del CatalogA.px
         del CatalogA.py
 
+    def test_bind_provider_with_valid_provided_type(self):
+        """Test setting of provider with provider type restriction."""
+        class SomeProvider(providers.Provider):
+            """Some provider."""
+
+        class SomeCatalog(catalogs.DeclarativeCatalog):
+            """Some catalog with provider type restriction."""
+
+            provider_type = SomeProvider
+
+        px = SomeProvider()
+        py = SomeProvider()
+
+        SomeCatalog.bind_provider('px', px)
+        SomeCatalog.py = py
+
+        self.assertIs(SomeCatalog.px, px)
+        self.assertIs(SomeCatalog.get_provider('px'), px)
+
+        self.assertIs(SomeCatalog.py, py)
+        self.assertIs(SomeCatalog.get_provider('py'), py)
+
+    def test_bind_provider_with_invalid_provided_type(self):
+        """Test setting of provider with provider type restriction."""
+        class SomeProvider(providers.Provider):
+            """Some provider."""
+
+        class SomeCatalog(catalogs.DeclarativeCatalog):
+            """Some catalog with provider type restriction."""
+
+            provider_type = SomeProvider
+
+        px = providers.Provider()
+
+        with self.assertRaises(errors.Error):
+            SomeCatalog.bind_provider('px', px)
+
+        with self.assertRaises(errors.Error):
+            SomeCatalog.px = px
+
+        with self.assertRaises(errors.Error):
+            SomeCatalog.bind_providers(dict(px=px))
+
     def test_bind_providers(self):
         """Test setting of provider via bind_providers() to catalog."""
         px = providers.Provider()