feat: add --platform flag to override haste.defaultPlatform

[tido64]

Summary

Adds a new flag, --platform, to override haste.defaultPlatform option. This is useful for tests that need to be run against multiple platform targets. Previously, you would need separate Jest configs for each platform and set haste.defaultPlatform accordingly. With this flag, you can have one config and instead specify --platform ios instead.

Test plan

Normally, running react-native tests without a haste configuration will fail:

test-app % yarn jest
 FAIL  test/App.test.tsx
  ● Test suite failed to run

    Cannot find module '../Libraries/Image/Image' from '../../node_modules/react-native/jest/setup.js'

      at Resolver.resolveModule (../../node_modules/jest-resolve/build/resolver.js:311:11)
      at Object.<anonymous> (../../node_modules/react-native/jest/setup.js:58:4)

Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        1.028 s
Ran all test suites.
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

With this change, you can now specify the platform from the command line:

% yarn jest --platform ios
 PASS  test/App.test.tsx
  ✓ renders correctly (239 ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        0.747 s
Ran all test suites.
✨  Done in 2.33s.

[codecov-commenter]

Codecov Report

Merging #11764 (cdbf2e3) into master (8d33ba1) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master   #11764      +/-   ##
==========================================
- Coverage   69.00%   68.98%   -0.02%     
==========================================
  Files         312      312              
  Lines       16339    16345       +6     
  Branches     4736     4740       +4     
==========================================
+ Hits        11275    11276       +1     
- Misses       5036     5041       +5     
  Partials       28       28              

Impacted Files	Coverage Δ
packages/jest-config/src/setFromArgv.ts	75.60% <0.00%> (-12.97%)	⬇️
packages/expect/src/utils.ts	96.13% <0.00%> (+0.55%)	⬆️

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[sigveio]

A changelog entry seems to be missing 🙂

[tido64]

A changelog entry seems to be missing 🙂

Thanks, I thought I pushed it already 😄

[tido64]

@SimenB: I would really appreciate it if you reviewed this PR and let me know how I can improve it.

[tido64]

@sigveio, @SimenB: Please let me know if there is someone else I can ping to help review this PR. Thanks 😄

[SimenB]

Hi! Sorry about the delay.

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Is there any reason you cannot use the existent --haste flag? I'd really love to not add any more flags 😅

[tido64]

Is there any reason you cannot use the existent --haste flag? I'd really love to not add any more flags 😅

Ah, it didn't occur to me that it exists (I combed through CLI options looking for it), even though I touched the code 😛

Does that mean that we could do something like --haste '{ defaultPlatform: "ios" }'? Compared to --platform ios, I think the latter is a lot more user-friendly, don't you think? It's not exactly what comes to mind if anyone asked me how to target a specific platform.

[mrazauskas]

@tido64 --haste='{"defaultPlatform": "ios"}' seems to be working. The value must be JSON string.

[SimenB]

I agree it's more user friendly, but a metric ton of options isn't very nice either... Also, passing both haste and this new flag would conflict, and which case should win isn't obvious to the end user I think regardless of which way we land it.

(And yeah, there's a bunch of CLI args we haven't documented - jest --help lists them all tho)

[github-actions]

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[github-actions]

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