The queueToDevice.spec.ts test suite is flaky

[robintown]

Me:

We seem to have an issue in our js-sdk tests somewhere with the new to-device message queue:

  ●  Cannot log after tests are done. Did you forget to wait for something async in your test?
    Attempted to log "All queued to-device messages sent".

      50 |             return console[methodName](...args);
      51 |         } else {
    > 52 |             return console.log(...args);
         |                            ^
      53 |         }
      54 |         /* eslint-enable no-console */
      55 |     };

      at console.log (node_modules/@jest/console/build/BufferedConsole.js:187:10)
      at Logger.log (src/logger.ts:52:28)
      at ToDeviceMessageQueue.debug [as sendQueue] (src/ToDeviceMessageQueue.ts:84:20)

This is coming out of the CI which suppresses most output so I can't see what test suite is causing it, and I can't reproduce it locally either. So, I guess this is a note to shout if anyone runs into it locally.

Travis:

I get different failures as a flake 😛
Expected 1 got 0 on a flush for the first one. Expected 20 got 1 on the object size for the second.

[dbkr]

I've increased the timeout on the flush in the above PR, but I can't repro the failure so I'm struggling to see how it would be possible for the code to only send one message in the request. It looks like mock-request does flush the requests in order so I don't think it's that the requests are getting mixed up.

[robintown]

I still got it to fail, even with the new timeout in place:

Summary of all failing tests
 FAIL  spec/unit/queueToDevice.spec.ts
  ● queueToDevice (IndexedDB store) › retries when a message is retried

    expect(received).toEqual(expected) // deep equality

    Expected: 1
    Received: 0

      301 |         });
      302 |
    > 303 |         expect(await httpBackend.flush(null, 1, 1)).toEqual(1);
          |                                                     ^
      304 |         await flushPromises();
      305 |
      306 |         const dummyEvent = new MatrixEvent({

      at Object.toEqual (spec/unit/queueToDevice.spec.ts:303:53)

  ● queueToDevice (IndexedDB store) › splits many messages into multiple HTTP requests

    expect(received).toEqual(expected) // deep equality

    Expected: 20
    Received: 1

      332 |             "PUT", "/sendToDevice/org.example.foo/",
      333 |         ).check((request) => {
    > 334 |             expect(Object.keys(request.data.messages).length).toEqual(20);
          |                                                               ^
      335 |         }).respond(200, {});
      336 |
      337 |         httpBackend.when(

      at Array.toEqual (spec/unit/queueToDevice.spec.ts:334:63)
      at HttpBackend._takeFromQueue (node_modules/matrix-mock-request/lib/index.js:217:34)
      at _tryFlush (node_modules/matrix-mock-request/lib/index.js:102:20)
      at Timeout.tryFlush [as _onTimeout] (node_modules/matrix-mock-request/lib/index.js:92:13)