From e2ed33f8b118020cd0e84b4c5266270f4723ee1f Mon Sep 17 00:00:00 2001
From: Chang Wang <garnwraly@gmail.com>
Date: Fri, 31 May 2019 18:27:27 -0400
Subject: [PATCH] Revert "Revert "Avoid duplicate `cacheControl` directives via
 `isDirectiveDefined` (#2428)""

This reverts commit c742335a4e745455bc51fbcac7fdab772c20cbc1.
---
 .../apollo-server-core/src/ApolloServer.ts    | 30 +++++++------
 .../src/__tests__/isDirectiveDefined.ts       | 44 +++++++++++++++++++
 .../src/utils/isDirectiveDefined.ts           | 13 ++++++
 3 files changed, 74 insertions(+), 13 deletions(-)
 create mode 100644 packages/apollo-server-core/src/__tests__/isDirectiveDefined.ts
 create mode 100644 packages/apollo-server-core/src/utils/isDirectiveDefined.ts

diff --git a/packages/apollo-server-core/src/ApolloServer.ts b/packages/apollo-server-core/src/ApolloServer.ts
index 9d4bfd4dcb1..708bfbc171b 100644
--- a/packages/apollo-server-core/src/ApolloServer.ts
+++ b/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,
@@ -270,19 +271,22 @@ 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');
diff --git a/packages/apollo-server-core/src/__tests__/isDirectiveDefined.ts b/packages/apollo-server-core/src/__tests__/isDirectiveDefined.ts
new file mode 100644
index 00000000000..e3353064f7b
--- /dev/null
+++ b/packages/apollo-server-core/src/__tests__/isDirectiveDefined.ts
@@ -0,0 +1,44 @@
+import { gql } from '../';
+import { isDirectiveDefined } from '../utils/isDirectiveDefined';
+
+describe('isDirectiveDefined', () => {
+  it('returns false when a directive is not defined', () => {
+    expect(
+      isDirectiveDefined(
+        [
+          gql`
+            type Query {
+              hello: String
+            }
+          `,
+        ],
+        'cacheControl',
+      ),
+    ).toBe(false);
+  });
+
+  it('returns true when a directive is defined', () => {
+    expect(
+      isDirectiveDefined(
+        [
+          gql`
+            type Query {
+              hello: String
+            }
+
+            enum CacheControlScope {
+              PUBLIC
+              PRIVATE
+            }
+
+            directive @cacheControl(
+              maxAge: Int
+              scope: CacheControlScope
+            ) on FIELD_DEFINITION | OBJECT | INTERFACE
+          `,
+        ],
+        'cacheControl',
+      ),
+    ).toBe(true);
+  });
+});
diff --git a/packages/apollo-server-core/src/utils/isDirectiveDefined.ts b/packages/apollo-server-core/src/utils/isDirectiveDefined.ts
new file mode 100644
index 00000000000..4523573b851
--- /dev/null
+++ b/packages/apollo-server-core/src/utils/isDirectiveDefined.ts
@@ -0,0 +1,13 @@
+import { DocumentNode, Kind } from 'graphql/language';
+
+export const isDirectiveDefined = (
+  typeDefs: DocumentNode[],
+  directiveName: string,
+) =>
+  typeDefs.some(typeDef =>
+    typeDef.definitions.some(
+      definition =>
+        definition.kind === Kind.DIRECTIVE_DEFINITION &&
+        definition.name.value === directiveName,
+    ),
+  );