Use reference-equality when omitting validation rules during composition.

packages/apollo-federation/CHANGELOG.md

@@ -4,6 +4,8 @@
 
 > The changes noted within this `vNEXT` section have not been released yet.  New PRs and commits which introduce changes should include an entry in this `vNEXT` section as part of their development.  When a release is being prepared, a new header will be (manually) created below and the the appropriate changes within that release will be moved into the new section.
 
+- Use reference-equality when omitting validation rules during composition. [#3338](https://github.com/apollographql/apollo-server/pull/3338)
+
 ### v0.10.0
 
 > [See complete versioning details.](https://github.com/apollographql/apollo-server/commit/6100fb5e0797cd1f578ded7cb77b60fac47e58e3)

packages/apollo-federation/src/composition/rules.ts

@@ -1,27 +1,59 @@
 import { specifiedSDLRules } from 'graphql/validation/specifiedRules';
 
+/**
+ * Since this module has overlapping names in the two modules (graphql-js and
+ * our own, local validation rules) which we are importing from, we
+ * intentionally are very explicit about the suffixes of imported members here,
+ * so that the intention is clear.
+ *
+ * First, we'll import validation rules from graphql-js which we'll omit and
+ * replace with our own validation rules. As noted above, we'll use aliases
+ * with 'FromGraphqlJs' suffixes for clarity.
+ */
+
+import {
+  UniqueDirectivesPerLocation as UniqueDirectivesPerLocationFromGraphqlJs,
+} from 'graphql/validation/rules/UniqueDirectivesPerLocation';
+import {
+  UniqueTypeNames as UniqueTypeNamesFromGraphqlJs,
+} from 'graphql/validation/rules/UniqueTypeNames';
+import {
+  UniqueEnumValueNames as UniqueEnumValueNamesFromGraphqlJs,
+} from 'graphql/validation/rules/UniqueEnumValueNames';
+import {
+  PossibleTypeExtensions as PossibleTypeExtensionsFromGraphqlJs,
+} from 'graphql/validation/rules/PossibleTypeExtensions';
+import {
+  UniqueFieldDefinitionNames as UniqueFieldDefinitionNamesFromGraphqlJs,
+} from 'graphql/validation/rules/UniqueFieldDefinitionNames';
+
+/**
+ * Then, we'll import our own validation rules to take the place of those that
+ * we'll be customizing, taking care to alias them all to the same name with
+ * "FromComposition" suffixes.
+ */
 import {
-  UniqueTypeNamesWithFields,
-  MatchingEnums,
-  PossibleTypeExtensions,
-  UniqueFieldDefinitionNames,
-  UniqueUnionTypes,
-} from './validate/sdl';
+  UniqueTypeNamesWithFields as UniqueTypeNamesWithFieldsFromComposition,
+  MatchingEnums as MatchingEnumsFromComposition,
+  PossibleTypeExtensions as PossibleTypeExtensionsFromComposition,
+  UniqueFieldDefinitionNames as UniqueFieldDefinitionsNamesFromComposition,
+  UniqueUnionTypes as UniqueUnionTypesFromComposition,
+ } from './validate/sdl';
 
 const omit = [
-  'UniqueDirectivesPerLocation',
-  'UniqueTypeNames',
-  'UniqueEnumValueNames',
-  'PossibleTypeExtensions',
-  'UniqueFieldDefinitionNames',
+  UniqueDirectivesPerLocationFromGraphqlJs,
+  UniqueTypeNamesFromGraphqlJs,
+  UniqueEnumValueNamesFromGraphqlJs,
+  PossibleTypeExtensionsFromGraphqlJs,
+  UniqueFieldDefinitionNamesFromGraphqlJs,
 ];
 
 export const compositionRules = specifiedSDLRules
-  .filter(rule => !omit.includes(rule.name))
+  .filter(rule => !omit.includes(rule))
   .concat([
-    UniqueFieldDefinitionNames,
-    UniqueTypeNamesWithFields,
-    MatchingEnums,
-    UniqueUnionTypes,
-    PossibleTypeExtensions,
+    UniqueFieldDefinitionsNamesFromComposition,
+    UniqueTypeNamesWithFieldsFromComposition,
+    MatchingEnumsFromComposition,
+    UniqueUnionTypesFromComposition,
+    PossibleTypeExtensionsFromComposition,
   ]);