Snapshot produced by toThrowErrorMatchingSnapshot might not match on CI

[okonet]

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

Using .toThrowErrorMatchingSnapshot() on code that prints error using ansi codes (i.e. using chalk) produces different snapshots if run locally or on CI.

I'm running using jest-validate and here is the test I wrote for it: https://github.com/okonet/lint-staged/pull/141/files#diff-bdc504f1ee32ed7f1704def433667f72R223

This test runs locally but fails on CI. See https://travis-ci.org/okonet/lint-staged/jobs/270725061

If the current behavior is a bug, please provide the steps to reproduce and either a repl.it demo through https://repl.it/languages/jest or a minimal repository on GitHub that we can yarn install and yarn test.

git clone git@github.com:okonet/lint-staged.git
cd lint-staged && npm install && npm test

This should be free of errors. Running same command on Travis CI will fail the build, though: https://travis-ci.org/okonet/lint-staged/jobs/270725061

What is the expected behavior?

Snapshots should match locally and on CI.

Please provide your exact Jest configuration and mention your Jest, node, yarn/npm version and operating system.

Default Jest config with babel-jest
macOS 10.12.
node 8.1.3
npm 5.3.0

[cpojer]

I don't think there is anything we can really do about this… If your terminal supports colors in one place but not in another, then the output may differ and toThrowErrorMatchingSnapshot may not be the right matcher for you, unfortunately :(

[cpojer]

I'm happy to reopen if there is a proposal that will work consistently, and happy to merge PRs.

[thymikee]

You can however create a custom serializer which will strip the colors if they don't matter

[cpojer]

Oh yeah, that's a good solution, I like that one.

[okonet]

@cpojer would you merge a PR for the default serializer that does that or adds an option?

[cpojer]

Nah, I think publishing that serializer in a separate package makes most sense to me. We can link to it from somewhere on the Jest docs, though (do we have a space for extensions to Jest there?).

[thymikee]

We should have a community section with known and reliable libs around Jest

[cpojer]

Agreed!

[gnapse]

Hi, I'm needing a serializer that performs exactly what was needed in this case, and I can't find it referenced in the docs. I found this community section and from there there's a link to "more resources" and to jest-awesome but I found no such serializer in those places.

[gnapse]

Ok we found one, and I'll link to it for future reference to others that pass by this issue:

https://github.com/joaogranado/jest-serializer-ansi

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