Avoid duplicate cacheControl directives via `isDirectiveDefin… (#2762)

* Revert "Revert "Avoid duplicate `cacheControl` directives via `isDirectiveDefined` (#2428)""

This reverts commit c742335.

* Account for typeDefs possibly being a string

* Add tests to ensure isDirectiveDefiend works for strings

* rename test file to add ".test"

* update changelog

CHANGELOG.md

@@ -6,6 +6,8 @@ The version headers in this history reflect the versions of Apollo Server itself
 
 > 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.
 
+- `apollo-server-core`: Avoid duplicate `cacheControl` directives being added via `isDirectiveDefined`. [PR #2762](https://github.com/apollographql/apollo-server/pull/2762) (was reverted in 2.6.1 because previous implementation released in 2.6.0 broke passing in typedefs as a string)
+
 ### v2.6.5
 
 - `apollo-engine-reporting`: Simplify the technique for capturing `operationName`. [PR #2899](https://github.com/apollographql/apollo-server/pull/2899)

packages/apollo-server-core/src/ApolloServer.ts

@@ -50,8 +50,9 @@ import {
   PlaygroundRenderPageOptions,
 } from './playground';
 
-import createSHA from './utils/createSHA';
 import { generateSchemaHash } from './utils/schemaHash';
+import { isDirectiveDefined } from './utils/isDirectiveDefined';
+import createSHA from './utils/createSHA';
 import {
   processGraphQLRequest,
   GraphQLRequestContext,
@@ -272,19 +273,22 @@ export class ApolloServerBase {
 
       // We augment the typeDefs with the @cacheControl directive and associated
       // scope enum, so makeExecutableSchema won't fail SDL validation
-      augmentedTypeDefs.push(
-        gql`
-          enum CacheControlScope {
-            PUBLIC
-            PRIVATE
-          }
 
-          directive @cacheControl(
-            maxAge: Int
-            scope: CacheControlScope
-          ) on FIELD_DEFINITION | OBJECT | INTERFACE
-        `,
-      );
+      if (!isDirectiveDefined(augmentedTypeDefs, 'cacheControl')) {
+        augmentedTypeDefs.push(
+          gql`
+            enum CacheControlScope {
+              PUBLIC
+              PRIVATE
+            }
+
+            directive @cacheControl(
+              maxAge: Int
+              scope: CacheControlScope
+            ) on FIELD_DEFINITION | OBJECT | INTERFACE
+          `,
+        );
+      }
 
       if (this.uploadsConfig) {
         const { GraphQLUpload } = require('graphql-upload');

packages/apollo-server-core/src/__tests__/isDirectiveDefined.test.ts

@@ -0,0 +1,47 @@
+import { gql } from '../';
+import { isDirectiveDefined } from '../utils/isDirectiveDefined';
+
+describe('isDirectiveDefined', () => {
+  const noCacheControl = `
+    type Query {
+      hello: String
+    }
+  `;
+  const hasCacheControl = `
+    type Query {
+      hello: String
+    }
+
+    enum CacheControlScope {
+      PUBLIC
+      PRIVATE
+    }
+
+    directive @cacheControl(
+      maxAge: Int
+      scope: CacheControlScope
+    ) on FIELD_DEFINITION | OBJECT | INTERFACE
+  `;
+
+  describe('When passed an array of DocumentNode', () => {
+    it('returns false when a directive is not defined', () => {
+      expect(isDirectiveDefined([gql(noCacheControl)], 'cacheControl')).toBe(
+        false,
+      );
+    });
+    it('returns true when a directive is defined', () => {
+      expect(isDirectiveDefined([gql(hasCacheControl)], 'cacheControl')).toBe(
+        true,
+      );
+    });
+  });
+
+  describe('When passed a string', () => {
+    it('returns false when a directive is not defined', () => {
+      expect(isDirectiveDefined(noCacheControl, 'cacheControl')).toBe(false);
+    });
+    it('returns true when a directive is defined', () => {
+      expect(isDirectiveDefined(hasCacheControl, 'cacheControl')).toBe(true);
+    });
+  });
+});

packages/apollo-server-core/src/utils/isDirectiveDefined.ts

@@ -0,0 +1,18 @@
+import { DocumentNode, Kind } from 'graphql/language';
+import { gql } from '../';
+
+export const isDirectiveDefined = (
+  typeDefs: DocumentNode[] | string,
+  directiveName: string,
+): boolean => {
+  if (typeof typeDefs === 'string') {
+    return isDirectiveDefined([gql(typeDefs)], directiveName);
+  }
+  return typeDefs.some(typeDef =>
+    typeDef.definitions.some(
+      definition =>
+        definition.kind === Kind.DIRECTIVE_DEFINITION &&
+        definition.name.value === directiveName,
+    ),
+  );
+};