fix: Parse.Query.subscribe() does not return a rejected promise on error in Cloud Code Triggers beforeConnect or beforeSubscribe (parse-community#1490)

BREAKING CHANGE: Calling `Parse.Query.subscribe()` will now return a rejected promise if an error is thrown in Cloud Code Triggers `beforeConnect` or `beforeSubscribe`; in previous releases a resolved promise was returned, even if subscribing failed and it was necessary to create an `error.on` listener to handle these errors (parse-community#1490)

Author: dblythy

integration/test/ParseLiveQueryTest.js

@@ -256,4 +256,56 @@ describe('Parse LiveQuery', () => {
     object.set({ foo: 'bar' });
     await object.save();
   });
+
+  it('live query can handle beforeConnect and beforeSubscribe errors', async () => {
+    await reconfigureServer({
+      cloud({ Cloud }) {
+        Cloud.beforeSubscribe('TestError', () => {
+          throw 'not allowed to subscribe';
+        });
+      },
+    });
+    const client = new Parse.LiveQueryClient({
+      applicationId: 'integration',
+      serverURL: 'ws://localhost:1337',
+      javascriptKey: null,
+      masterKey: null,
+      sessionToken: null,
+      installationId: null,
+    });
+    client.open();
+    const query = new Parse.Query('TestError');
+    const subscription = client.subscribe(query);
+    await expectAsync(subscription.subscribePromise).toBeRejectedWith(
+      new Parse.Error(141, 'not allowed to subscribe')
+    );
+    client.close();
+  });
+
+  it('connectPromise does throw', async () => {
+    await reconfigureServer({
+      cloud({ Cloud }) {
+        Cloud.beforeConnect((params) => {
+          if (params.sessionToken === 'testToken') {
+            throw 'not allowed to connect';
+          }
+        });
+      },
+    });
+    const client = new Parse.LiveQueryClient({
+      applicationId: 'integration',
+      serverURL: 'ws://localhost:1337',
+      javascriptKey: null,
+      masterKey: null,
+      sessionToken: 'testToken',
+      installationId: null,
+    });
+    client.open();
+    const query = new Parse.Query('TestError');
+    const subscription = client.subscribe(query);
+    await expectAsync(subscription.subscribePromise).toBeRejectedWith(
+      new Parse.Error(141, 'not allowed to connect')
+    );
+    client.close();
+  });
 });

src/LiveQueryClient.js

@@ -14,6 +14,7 @@ import EventEmitter from './EventEmitter';
 import ParseObject from './ParseObject';
 import LiveQuerySubscription from './LiveQuerySubscription';
 import { resolvingPromise } from './promiseUtils';
+import ParseError from './ParseError';
 
 // The LiveQuery client inner state
 const CLIENT_STATE = {
@@ -217,9 +218,13 @@ class LiveQueryClient extends EventEmitter {
     const subscription = new LiveQuerySubscription(this.requestId, query, sessionToken);
     this.subscriptions.set(this.requestId, subscription);
     this.requestId += 1;
-    this.connectPromise.then(() => {
-      this.socket.send(JSON.stringify(subscribeRequest));
-    });
+    this.connectPromise
+      .then(() => {
+        this.socket.send(JSON.stringify(subscribeRequest));
+      })
+      .catch(error => {
+        subscription.subscribePromise.reject(error);
+      });
 
     return subscription;
   }
@@ -382,10 +387,15 @@ class LiveQueryClient extends EventEmitter {
         setTimeout(() => subscription.emit(SUBSCRIPTION_EMMITER_TYPES.OPEN, response), 200);
       }
       break;
-    case OP_EVENTS.ERROR:
+    case OP_EVENTS.ERROR: {
+      const parseError = new ParseError(data.code, data.error);
+      if (!this.id) {
+        this.connectPromise.reject(parseError);
+        this.state = CLIENT_STATE.DISCONNECTED;
+      }
       if (data.requestId) {
         if (subscription) {
-          subscription.subscribePromise.resolve();
+          subscription.subscribePromise.reject(parseError);
           setTimeout(() => subscription.emit(SUBSCRIPTION_EMMITER_TYPES.ERROR, data.error), 200);
         }
       } else {
@@ -398,6 +408,7 @@ class LiveQueryClient extends EventEmitter {
         this._handleReconnect();
       }
       break;
+    }
     case OP_EVENTS.UNSUBSCRIBED:
       // We have already deleted subscription in unsubscribe(), do nothing here
       break;