[Bug]: snapshot diff colors are unreadable in GitLab CI

[jakub-g]

Version

30.2.0

Steps to reproduce

Have a snapshot test that fails.

Expected behavior

It should also render readable colors in Gitlab CI.

Actual behavior

When ran on Gitlab CI, it renders unreadable colors.

Environment

GitLab CE 17.8.7

(It's been like this for years, nothing new)

Additional context

After some debugging, this is because chalk detects GitLab to be "level 1" color support, so the code paths are those:

• jest/packages/jest-snapshot/src/printSnapshot.ts

  Line 82 in f459dd6

  return chalkInstance.cyan.bgWhiteBright; // also known as teal

• jest/packages/jest-snapshot/src/printSnapshot.ts

  Line 64 in f459dd6

  return chalkInstance.magenta.bgYellowBright;

The problem is, GitLab for some reason doesn't properly render certain color combinations:

• c.bgWhiteBright.<someFgColor> never renders white bg
• c.<someFgColor>.bgBrightWhite always renders white-on-white

I'll get back to this once I have more bandwidth.