How to use fetch mocking and msw together

[wslp12]

I'm currently using msw well, but I don't have a clue what to do about certain jest taunts. So I'm looking for help.

const someData = jest.fn();
jest.spyOn(window, "fetch").mockImplementation(url => {
  switch(url) {
    case: "someUrl":
      return someData();
    default: wantMsw; // <- I'd like to work on this part to msw 
  }
});
...
expect(someData).toHaveBeenCalledTimes(1);

I'm originally using msw, so i don't have to mock fetch
But I'm inevitably mokcing fetch because I'm currently couting the numbers that certain url called,

However, since there is no need to mock all api, I would like to delegate the task to the handler of msw again in the default value of switch Will it be possible ?

[kettanaito]

Hi, @wslp12. Here's what I suggest.

1. Drop the fetch mock entirely.
2. To count the number of requests, do that in the matching request handler from MSW:

test('your test', () => {
  let requestCallCount = 0

  server.use(
    http.get('/some-url', () => {
      requestCallCount++
      // ...handle or passthrough this request.
    })
  )
})

You can return nothing from a request handler. In that case, MSW will try to look up another matching handler for the same request. If it finds none, the request will be performed as-is. That is likely not what you want in tests because you always want to mock the network and focus on what your network-dependent logic is doing (like counting request calls above).

Please also see Execution order for request handlers. That might help.