Fix incorrect request body when intercepting fetch with getMiniflareFetchMock

[robertcepa]

Hey there!

I am using miniflare with jest to test a Workers library. I need to write a simple unit test that intercepts a request body and returns it in response.

Example (full code here):

fetchMock.get('...')
  .intercept({
    method: () => true,
    path: () => true,
  })
  .reply(200, (opts) => {
    return opts;
  });

The issue I'm encountering is that opts.body doesn't contain request body string, as expected per https://undici.nodejs.org/#/docs/best-practices/mocking-request?id=reply-with-data-based-on-request , but AsyncGenerator.

I first thought that this was an issue in undici but after discussion with their team (nodejs/undici#1756) it seems that the solution is to expose isMockActive property on Dispatcher for test utilities on MockAgent to work properly.

This PR adds a new MiniflareDispatcherMock class that extends the base MiniflareDispatcher with isMockActive getter. I decided to not add the getter directly to MiniflareDispatcher, because it's a testing function that doesn't exist on real dispatchers.

This class is used on fetch polyfill to instantiate dispatcher when bound with MockAgent.

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[mrbbot]

Hey! 👋 Thanks for the PR! Added a small comment. 👍

[sjblurton]

Well done @robertcepa this is something we have been trying to work around here. Thank you for the PR.

Hey @mrbbot, we have been trying to get this working here since mid-last year and have just noticed someone has already fixed it. Do you have any idea when this will be released? Thank you.

[ashleyoldershaw]

Hi! I'm also invested in seeing this released :) do we have a timeline?

[sjblurton]

@mrbbot was talking about this PR today with the team. Is there a plan for a wide release? The automated testing we are trying to implement needs this.

[sjblurton]

Can we get any updates on this one, please? We really want to be able to test our API. 😁

[CameronB15]

Just stumbled across this PR when trying to figure out how to unit test my worker. Do you know when this will be added to a release @mrbbot?

[mrbbot]

Hey! Miniflare 2.12.0 has just been released with this change! 🙂 Apologies for the delay here.