Support promises and returning matcher from test

[dobesv]

What

Feature: support async returns from matchers

Why

If you want to use jest-chain and you also need to return a Promise from your test function. Without this change, jest-chain will throw away all the promises.

Notes

This makes jest-chain always return a promise. The promise also has all the matchers available on it. If a matcher in the chain returns a promise, the promise returned by chained matchers will depend on that promise.

Housekeeping

• [x] Unit tests
• [x] Documentation is up to date
• [x] No additional lint warnings

[codecov-io]

Codecov Report

Merging #11 into master will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #11   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines           23        24    +1     
  Branches         3         4    +1     
=========================================
+ Hits            23        24    +1     

Impacted Files	Coverage Δ
src/chain.js	100.00% <100.00%> (ø)

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[dobesv]

May supersede https://github.com/mattphillips/jest-chain/pull/9

[dobesv]

Fixes https://github.com/mattphillips/jest-chain/issues/8

[dobesv]

Fixes https://github.com/mattphillips/jest-chain/issues/1

[dobesv]

@mattphillips I resolved the conflicts, in case you were waiting for that. Let me know if there's anything else I can do to move this one forwards.

[tonivj5]

ey, @mattphillips, is it going to be merged? :+1:

[dobesv]

I've also updated the typing to reflect that rejects and resolves return a promise that also has matchers on it.

[RA80533]

/cc @mattphillips

[sepehr]

Would love to see this merged. Thank you @dobesv for your work on this.

[twawszczak-wr]

@mattphillips is it possible to merge that priceless PR?

[mattphillips]

Sorry for the delay in coming to this! The promises issue has been fixed in: https://www.npmjs.com/package/jest-chain/v/1.1.6

As for returning chained matchers (synchronous ones) inside of a promise to allow returning expect I'm not too sure this is a good idea and if it will cause existing tests to break so have for now chosen not to support this as it deviates from Jests behaviour.

I've added a skipped test for this for future reference https://github.com/mattphillips/jest-chain/blob/da5a0e0e5d19668cf8b24a6e84168beba37855b0/src/index.test.js#L56