Restrict overriding of providers with themselves

dependency_injector/providers.py

@@ -46,6 +46,9 @@ class Provider(object):
 
     def override(self, provider):
         """Override provider with another provider."""
+        if provider is self:
+            raise Error('Provider {0} could not be overridden '
+                        'with itself'.format(self))
         if not self.is_overridden:
             self.overridden_by = (ensure_is_provider(provider),)
         else:

tests/test_providers.py

@@ -65,6 +65,10 @@ class ProviderTests(unittest.TestCase):
         self.provider.override(overriding_provider)
         self.assertTrue(self.provider.is_overridden)
 
+    def test_override_with_itself(self):
+        """Test provider overriding with itself."""
+        self.assertRaises(di.Error, self.provider.override, self.provider)
+
     def test_override_with_not_provider(self):
         """Test provider overriding with not provider instance."""
         self.assertRaises(di.Error, self.provider.override, object())