Merge pull request #118 from PhiloInc/backport

Minor fixes to package

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ### vNEXT
 
+### 0.5.5
+- FilterFn can return a Promise<boolean>
+- Allow passing in a custom `EventEmitter` to `PubSub`
+
 ### 0.5.4
 - Better define `withFilter` return type [PR #111](https://github.com/apollographql/graphql-subscriptions/pull/111)
 

README.md

@@ -43,9 +43,8 @@ schema {
 }
 ```
 
-Now, let's create a simple `PubSub` instance - it is a simple pubsub implementation, based on `EventEmitter`.
-
-To create a simple `PubSub` instance, do the following:
+Now, let's create a simple `PubSub` instance - it is a simple pubsub implementation, based on `EventEmitter`. Alternative `EventEmitter` implementations can be passed by an options object
+to the `PubSub` constructor.
 
 ```js
 import { PubSub } from 'graphql-subscriptions';

package.json

@@ -1,6 +1,6 @@
 {
   "name": "graphql-subscriptions",
-  "version": "0.5.4",
+  "version": "0.5.5",
   "description": "GraphQL subscriptions for node.js",
   "main": "dist/index.js",
   "repository": {

src/index.ts

@@ -1,3 +1,3 @@
 export { PubSubEngine } from './pubsub-engine';
-export { PubSub } from './pubsub';
+export { PubSub, PubSubOptions } from './pubsub';
 export { withFilter, ResolverFn, FilterFn } from './with-filter';

src/pubsub.ts

@@ -2,13 +2,17 @@ import { EventEmitter } from 'events';
 import { PubSubEngine } from './pubsub-engine';
 import { eventEmitterAsyncIterator } from './event-emitter-to-async-iterator';
 
+export interface PubSubOptions {
+  eventEmitter?: EventEmitter;
+}
+
 export class PubSub implements PubSubEngine {
   protected ee: EventEmitter;
   private subscriptions: { [key: string]: [string, (...args: any[]) => void] };
   private subIdCounter: number;
 
-  constructor() {
-    this.ee = new EventEmitter();
+  constructor(options: PubSubOptions = {}) {
+    this.ee = options.eventEmitter || new EventEmitter();
     this.subscriptions = {};
     this.subIdCounter = 0;
   }

src/test/asyncIteratorSubscription.ts

@@ -7,7 +7,7 @@ import * as sinonChai from 'sinon-chai';
 
 import { isAsyncIterable } from 'iterall';
 import { PubSub } from '../pubsub';
-import { withFilter } from '../with-filter';
+import { withFilter, FilterFn } from '../with-filter';
 import { ExecutionResult } from 'graphql';
 
 chai.use(chaiAsPromised);
@@ -27,7 +27,7 @@ const FIRST_EVENT = 'FIRST_EVENT';
 
 const defaultFilter = (payload) => true;
 
-function buildSchema(iterator, filterFn = defaultFilter) {
+function buildSchema(iterator, filterFn: FilterFn = defaultFilter) {
   return new GraphQLSchema({
     query: new GraphQLObjectType({
       name: 'Query',
@@ -82,6 +82,31 @@ describe('GraphQL-JS asyncIterator', () => {
     return r;
   });
 
+  it('should allow async filter', async () => {
+    const query = parse(`
+      subscription S1 {
+
+        testSubscription
+      }
+    `);
+    const pubsub = new PubSub();
+    const origIterator = pubsub.asyncIterator(FIRST_EVENT);
+    const schema = buildSchema(origIterator, () => Promise.resolve(true));
+
+    const results = await subscribe(schema, query) as AsyncIterator<ExecutionResult>;
+    const payload1 = results.next();
+
+    expect(isAsyncIterable(results)).to.be.true;
+
+    const r = payload1.then(res => {
+      expect(res.value.data.testSubscription).to.equal('FIRST_EVENT');
+    });
+
+    pubsub.publish(FIRST_EVENT, {});
+
+    return r;
+  });
+
   it('should detect when the payload is done when filtering', (done) => {
     const query = parse(`
       subscription S1 {

src/with-filter.ts

@@ -1,6 +1,6 @@
 import { $$asyncIterator } from 'iterall';
 
-export type FilterFn = (rootValue?: any, args?: any, context?: any, info?: any) => boolean;
+export type FilterFn = (rootValue?: any, args?: any, context?: any, info?: any) => boolean | Promise<boolean>;
 export type ResolverFn = (rootValue?: any, args?: any, context?: any, info?: any) => AsyncIterator<any>;
 
 export const withFilter = (asyncIteratorFn: ResolverFn, filterFn: FilterFn): ResolverFn => {