Generator function as resolver that yields different responses depending on searchParams

[hzpz]

Hello everyone,

I am trying to test code that polls the same URL with different search parameters. Following the documentation for polling I implemented the resolver as a generator function like this:

const HITS = [24.0, 32.0, 48.0];
const MISSES = [8.0, 8.0, 16.0];

[...]

function* ({ request }) {
  const url = new URL(request.url);
  const tags = url.searchParams.getAll('tag');

  if (tags.includes('result:hit')) {
    for (let i = 0; i < HITS.length; i++) {
      yield HttpResponse.json({
        measurements: [{ value: HITS[i] }],
      });
    }

    return HttpResponse.json({
      measurements: [{ value: HITS[HITS.length - 1] }],
    });
  } else if (tags.includes('result:miss')) {
    for (let i = 0; i < MISSES.length; i++) {
      yield HttpResponse.json({
        measurements: [{ value: MISSES[i] }],
      });
    }

    return HttpResponse.json({
      measurements: [{ value: MISSES[MISSES.length - 1] }],
    });
  }
},

The first two requests, one with tag=result:hit and the other with tag=result:miss work perfectly fine returning 24.0 and 8.0. But after that, msw will only return values from the "misses" branch, even if the request was made with tag=result:hit. That is, the next values are 8.0 and then 16.0. indefinitly, regardless of search parameters.

What am I doing wrong?

Any help is much appreciated!

[kettanaito]

Hi, @hzpz. Thanks for raising this.

From what you've provided, it looks like a bug in MSW. Can you please create a minimal reproduction repo for this? Alternatively, you can open a pull request with a failing test, that would help fixing this even faster.

Thanks.