Fix apollo-server-core runQuery breaks async_hook tracking (#733)

By creating a promise out of the execution flow the ability to trace the
async call stack is lost.

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changelog
 
 ### vNEXT
+* Fix apollo-server-core runQuery breaks async_hooks tracking [PR #733](https://github.com/apollographql/apollo-server/pull/733)
 
 ### v1.3.0
 * Added support for the vhost option for Hapi [PR #611](https://github.com/apollographql/apollo-server/pull/611)

packages/apollo-server-core/src/runQuery.test.ts

@@ -315,4 +315,48 @@ describe('runQuery', () => {
           },
       });
     });
+
+    describe('async_hooks', () => {
+        let asyncHooks;
+        let asyncHook;
+        const ids: number[] = [];
+
+        try {
+            asyncHooks = require('async_hooks');
+        } catch (err) {
+            return; // async_hooks not present, give up
+        }
+
+        before(() => {
+            asyncHook = asyncHooks.createHook({ init: (asyncId) => ids.push(asyncId) });
+            asyncHook.enable();
+        });
+
+        after(() => {
+            asyncHook.disable();
+        });
+
+        it('does not break async_hook call stack', async () => {
+            const query = `
+              query Q1 {
+                testObject {
+                  testString
+                }
+              }
+            `;
+
+            await runQuery({
+                schema,
+                query: query,
+                operationName: 'Q1',
+            });
+
+            // this is the only async process so we expect the async ids to be a sequence
+            ids.forEach((id, i) => {
+                if (i > 0) {
+                    expect(id).to.equal(ids[i - 1] + 1);
+                }
+            });
+        });
+    });
 });

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

@@ -62,11 +62,9 @@ export interface QueryOptions {
  cacheControl?: boolean;
 }
 
-const resolvedPromise = Promise.resolve();
-
 function runQuery(options: QueryOptions): Promise<GraphQLResponse> {
     // Fiber-aware Promises run their .then callbacks in Fibers.
-    return resolvedPromise.then(() => doRunQuery(options));
+    return Promise.resolve().then(() => doRunQuery(options));
 }
 
 function doRunQuery(options: QueryOptions): Promise<GraphQLResponse> {