feat(jest-expect): re-export Matchers and MatcherFunctionWithState interface

[mrazauskas]

Summary

Perhaps jest-expect should re-export Matchers interface as well?

I was looking at the example again. Feels like Jest users should be recommended to extend interfaces from '@jest/expect' instead of 'expect'. Right? In this case Matchers must be re-exported from jest-expect.

Also MatcherFunctionWithState is also useful. It is just the same as MatcherFunction, but takes two generic type arguments (state and matcher args) instead of one (only matcher args). I guess in most of the cases MatcherFunction will do the job, but for more advance usage MatcherFunctionWithState will be helpful too.

Other problem. Because of augmentation the example was pulling types from test type files. Ups.. I added minimal tsconfig.json, which helps to isolate the example.

Test plan

Green CI.

[SimenB]

Hmm, it depends! Are the matchers for Jest specifically, or expect (which can be used anywhere standalone, like in mocha) generically?

Snapshots need runtime support, so makes sense for them to be separate, but I'd assume most matchers doesn't need that and can safely extend the base expect?

Doesn't hurt to re-export of course, but unsure of changing the example

[mrazauskas]

Agreed. The example is reverted.

[mrazauskas]

What about this? If 'expect' is extended later, perhaps importing from 'expect' here makes sense? Or?

[SimenB]

agreed!

[SimenB]

at least, I agree if this example is "extend expect" and not "extend jest with extra matcher". In that case people should import from @jest/globals (or use the global whenever we fix that)

[mrazauskas]

Hm.. Perhaps I will revert this. In my head this was "extend jest with extra matcher" example. I mean, there is an extra file where this new matcher is used in a test. If expect was extended not for Jest, then expect(100).toBeWithinRange(90, 110); line in this file would be enough without extra test file. It makes sense to import from '@jest/globals'.

[SimenB]

👍

We should work on https://jestjs.io/docs/expect to give better examples there probably, but keep this example as is

[mrazauskas]

Agreed (;

[SimenB]

👍

[SimenB]

Out in https://github.com/facebook/jest/releases/tag/v28.0.0-alpha.3 fwiw

[github-actions]

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