fix: do not send GQL_STOP after GQL_COMPLETED is received

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 
+### vNEXT
+- Do not send GQL_STOP when unsubscribing after GQL_COMPLETE is received [Issue #765](https://github.com/apollographql/subscriptions-transport-ws/issues/711)
+
 ### v0.9.17
 
 - Bump `graphql` peer/dev deps.  <br/>

src/client.ts

@@ -623,8 +623,9 @@ export class SubscriptionClient {
         break;
 
       case MessageTypes.GQL_COMPLETE:
-        this.operations[opId].handler(null, null);
+        const handler = this.operations[opId].handler;
         delete this.operations[opId];
+        handler.call(this, null, null);
         break;
 
       case MessageTypes.GQL_ERROR:

src/test/tests.ts

@@ -1195,6 +1195,33 @@ describe('Client', function () {
     done();
   });
 
+  it('should not send GQL_STOP on unsubscribe after operation received a GQL_COMPLETE', (done) => {
+    const client = new SubscriptionClient(`ws://localhost:${TEST_PORT}/`);
+    const sendMessageSpy = sinon.spy(client as any, 'sendMessage');
+
+    client.onConnected(() => {
+      const subscription = client.request({
+        query: `subscription { somethingChanged }`,
+        variables: {},
+      }).subscribe({
+        next: () =>  {
+          client.client.onmessage({
+            data: JSON.stringify({id: 1, type: MessageTypes.GQL_COMPLETE}),
+          });
+        },
+        complete: () => {
+          subscription.unsubscribe();
+        },
+      });
+      setTimeout(() => {
+        expect(sendMessageSpy.calledWith(undefined, 'connection_init', sinon.match.any)).to.be.true;
+        expect(sendMessageSpy.calledWith('1', 'start', sinon.match.any)).to.be.true;
+        expect(sendMessageSpy.calledWith('1', 'stop', sinon.match.any)).to.be.false;
+        done();
+      }, 1000);
+    });
+  });
+
   it('should delete operation when receive a GQL_COMPLETE', (done) => {
     const subscriptionsClient = new SubscriptionClient(`ws://localhost:${RAW_TEST_PORT}/`);
     subscriptionsClient.operations['1'] = {

src/utils/empty-iterable.ts

@@ -16,5 +16,5 @@ export const createEmptyIterable = (): EmptyIterable => {
     [$$asyncIterator]() {
       return this;
     },
-  };
+  } as any;
 };