Add a failing test for printSnapshotAndReceived incorrectly recognizing sometimes indented lines as changed

[Andarist]

Summary

It has been reported to Emotion that each printed style property is being shown as changed in Jest 25 when anything changes between snapshots & received: https://github.com/emotion-js/emotion/issues/1847

It turned out that we currently ignore indentation because we use OldPlugin interface and we just print retrieved styles with always indented. We plan to fix this soon, but I believe the issue is still worth fixing in Jest itself - especially that the comment here: https://github.com/facebook/jest/blob/32aaff83f02c347ccd591727544002490fb4ee9a/packages/jest-snapshot/src/printSnapshot.ts#L316-L317 suggests that this was supposed to be handled.

So far I've just added a failing test and would like to first check-in if there is an interest in fixing this before I dive into this further. I've also actually tried to fix this quickly by calling dedentLines on this: https://github.com/facebook/jest/blob/32aaff83f02c347ccd591727544002490fb4ee9a/packages/jest-snapshot/src/printSnapshot.ts#L324 but while it has fixed my issue it has changed 2 other tests and it would require further investigation why this is happening and how the fix could be improved.

[SimenB]

Thanks @Andarist, failing tests are the best bug reports ever! 😀

@pedrottimark @jeysal any ideas here?

[Andarist]

Just an additional note because it might not be super clear while skimming through my original post - this has changed between Jest 24 and Jest 25. Jest 24 did not report those false positives.

[SimenB]

Either I messed up the merge or this is fixed. @Andarist any idea? 😀

[codecov-commenter]

Codecov Report

Merging #9863 (1e57d0e) into main (e3c84b5) will increase coverage by 0.00%. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #9863   +/-   ##
=======================================
  Coverage   68.47%   68.48%           
=======================================
  Files         324      324           
  Lines       16968    16968           
  Branches     5060     5060           
=======================================
+ Hits        11619    11620    +1     
+ Misses       5317     5316    -1     
  Partials       32       32           

Impacted Files	Coverage Δ
packages/jest-snapshot/src/plugins.ts	100.00% <0.00%> (+20.00%)	:arrow_up:

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[Andarist]

@SimenB This PR was sent quite some time ago - there is a high chance of this being fixed now so perhaps this can be closed. I would probably recommend trying to check if there is already a test for this because if there is not then maybe it's still worth landing this PR so this test could act as a regression test for the future.

I'm afraid that I won't have enough time to look into this myself though.

[SimenB]

I'm happy to land this as a regression test 🙂

[SimenB]

Ah wait no, the test demonstrates the error, it wasn't a failing test. Makes sense! Ref https://github.com/facebook/jest/pull/9863#discussion_r413071029

[Andarist]

Ah, so the problem is still here - I just didn't make it a failing test case back then but rather a test showcasing an invalid behavior, did I get this right (I'm refreshing my own memory about this issue)?

[SimenB]

yeah, seems like it to me 🙂

[github-actions[bot]]

This PR is stale because it has been open 1 year with no activity. Remove stale label or comment or this will be closed in 30 days.

[Andarist]

bump for stale bot

[github-actions[bot]]

This PR is stale because it has been open 1 year with no activity. Remove stale label or comment or this will be closed in 30 days.

[Andarist]

bump for stale bot