Restrict overriding of catalogs by themselves

dependency_injector/catalogs.py

@@ -7,6 +7,7 @@ from .errors import UndefinedProviderError
 
 from .utils import is_provider
 from .utils import is_catalog
+from .utils import is_declarative_catalog
 from .utils import ensure_is_provider
 from .utils import ensure_is_catalog_bundle
 
@@ -254,8 +255,14 @@ class DynamicCatalog(object):
         :type overriding: :py:class:`DeclarativeCatalog` |
                           :py:class:`DynamicCatalog`
 
+        :raise: :py:exc:`dependency_injector.errors.Error` if trying to
+                override catalog by itself
+
         :rtype: None
         """
+        if overriding is self:
+            raise Error('Catalog {0} could not be overridden '
+                        'with itself'.format(self))
         self.overridden_by += (overriding,)
         for name, provider in six.iteritems(overriding.providers):
             self.get_provider(name).override(provider)
@@ -673,8 +680,14 @@ class DeclarativeCatalog(object):
         :type overriding: :py:class:`DeclarativeCatalog` |
                           :py:class:`DynamicCatalog`
 
+        :raise: :py:exc:`dependency_injector.errors.Error` if trying to
+                override catalog by itself or its subclasses
+
         :rtype: None
         """
+        if is_declarative_catalog(overriding) and issubclass(cls, overriding):
+            raise Error('Catalog {0} could not be overridden '
+                        'with itself or its subclasses'.format(cls))
         return cls._catalog.override(overriding)
 
     @classmethod

tests/test_catalogs.py

@@ -474,6 +474,23 @@ class OverrideTests(unittest.TestCase):
         self.assertEqual(CatalogA.p12(), 2)
         self.assertEqual(len(CatalogA.overridden_by), 1)
 
+    def test_override_declarative_catalog_with_itself(self):
+        """Test catalog overriding of declarative catalog with itself."""
+        with self.assertRaises(errors.Error):
+            CatalogA.override(CatalogA)
+
+    def test_override_declarative_catalog_with_subclass(self):
+        """Test catalog overriding of declarative catalog with subclass."""
+        with self.assertRaises(errors.Error):
+            CatalogB.override(CatalogA)
+
+    def test_override_dynamic_catalog_with_itself(self):
+        """Test catalog overriding of dynamic catalog with itself."""
+        catalog = catalogs.DynamicCatalog(p11=providers.Value(1),
+                                          p12=providers.Value(2))
+        with self.assertRaises(errors.Error):
+            catalog.override(catalog)
+
     def test_overriding_with_dynamic_catalog(self):
         """Test catalog overriding with another dynamic catalog."""
         CatalogA.override(catalogs.DynamicCatalog(p11=providers.Value(1),