Preserve the extensions property when pre-execution errors occur.

CHANGELOG.md

@@ -8,6 +8,7 @@ The version headers in this history reflect the versions of Apollo Server itself
 
 - `@apollo/gateway`, `@apollo/federation`, `apollo-engine-reporting`: Update `apollo-graphql` dependency to bring in [`apollo-tooling`'s #1551](https://github.com/apollographql/apollo-tooling/pull/1551) which resolve runtime errors when its source is minified.  While this fixes a particular minification bug when Apollo Server packages are minified, we _do not_ recommend minification of server code in most cases. [PR #3387](https://github.com/apollographql/apollo-server/pull/3387) [Issue #3335](https://github.com/apollographql/apollo-server/issues/3335)
 - `apollo-server-koa`: Correctly declare dependency on `koa-compose`. [PR #3356](https://github.com/apollographql/apollo-server/pull/3356)
+- `apollo-server-core`: Preserve any `extensions` that have been placed on the response when pre-execution errors occur. [PR #3394](https://github.com/apollographql/apollo-server/pull/3394)
 
 ### v2.9.3
 

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

@@ -4,6 +4,7 @@ import {
   resolveGraphqlOptions,
 } from './graphqlOptions';
 import {
+  ApolloError,
   formatApolloErrors,
   PersistedQueryNotSupportedError,
   PersistedQueryNotFoundError,
@@ -18,7 +19,7 @@ import {
 } from './requestPipeline';
 import { CacheControlExtensionOptions } from 'apollo-cache-control';
 import { ApolloServerPlugin } from 'apollo-server-plugin-base';
-import { WithRequired } from 'apollo-server-types';
+import { WithRequired, GraphQLExecutionResult } from 'apollo-server-types';
 
 export interface HttpQueryRequest {
   method: string;
@@ -75,6 +76,7 @@ export function throwHttpGraphQLError<E extends Error>(
   statusCode: number,
   errors: Array<E>,
   options?: Pick<GraphQLOptions, 'debug' | 'formatError'>,
+  extensions?: GraphQLExecutionResult['extensions'],
 ): never {
   const defaultHeaders = { 'Content-Type': 'application/json' };
   // force no-cache on PersistedQuery errors
@@ -84,16 +86,27 @@ export function throwHttpGraphQLError<E extends Error>(
         'Cache-Control': 'private, no-cache, must-revalidate',
       }
     : defaultHeaders;
+
+  type Result =
+   & Pick<GraphQLExecutionResult, 'extensions'>
+   & { errors: E[] | ApolloError[] }
+
+  const result: Result = {
+    errors: options
+      ? formatApolloErrors(errors, {
+          debug: options.debug,
+          formatter: options.formatError,
+        })
+      : errors,
+  };
+
+  if (extensions) {
+    result.extensions = extensions;
+  }
+
   throw new HttpQueryError(
     statusCode,
-    prettyJSONStringify({
-      errors: options
-        ? formatApolloErrors(errors, {
-            debug: options.debug,
-            formatter: options.formatError,
-          })
-        : errors,
-    }),
+    prettyJSONStringify(result),
     true,
     headers,
   );
@@ -303,6 +316,8 @@ export async function processHTTPRequest<TContext>(
           return throwHttpGraphQLError(
             (response.http && response.http.status) || 400,
             response.errors as any,
+            undefined,
+            response.extensions,
           );
         }
 

packages/apollo-server-integration-testsuite/src/ApolloServer.ts

@@ -570,6 +570,48 @@ export function testApolloServer<AS extends ApolloServerBase>(
         expect(result.errors).toBeDefined();
         expect(apolloFetchResponse.status).toEqual(403);
       });
+
+      it('preserves user-added "extensions" in the response when parsing errors occur', async () => {
+        await setupApolloServerAndFetchPairForPlugins([
+          {
+            requestDidStart() {
+              return {
+                willSendResponse({ response }) {
+                  response.extensions = { myExtension: true };
+                },
+              };
+            },
+          },
+        ]);
+
+        const result =
+          await apolloFetch({ query: '{ 🦠' });
+        expect(result.errors).toBeDefined();
+        expect(result.extensions).toEqual(expect.objectContaining({
+          myExtension: true
+        }));
+      });
+
+      it('preserves user-added "extensions" in the response when validation errors occur', async () => {
+        await setupApolloServerAndFetchPairForPlugins([
+          {
+            requestDidStart() {
+              return {
+                willSendResponse({ response }) {
+                  response.extensions = { myExtension: true };
+                },
+              };
+            },
+          },
+        ]);
+
+        const result =
+          await apolloFetch({ query: '{ missingFieldWhichWillNotValidate }' });
+        expect(result.errors).toBeDefined();
+        expect(result.extensions).toEqual(expect.objectContaining({
+          myExtension: true
+        }));
+      });
     });
 
     describe('formatError', () => {