Snapshot comparison failing but results look identical

🐛 Bug Report

A unit test is failing in one environment but not others. The output is very unhelpful because the serialized results look identical.

To Reproduce

Created a unit tests against captured console output using toMatchSnapshot().

    expect(getLog().log).toMatchSnapshot()

The results of running this test look like this:

[2020-04-22T17:27:08.927Z] FAIL src/__tests__/logger.test.js
[2020-04-22T17:27:08.927Z]   ● Console logging › Logs error level and above.
[2020-04-22T17:27:08.927Z]
[2020-04-22T17:27:08.927Z]     expect(received).toMatchSnapshot()
[2020-04-22T17:27:08.927Z]
[2020-04-22T17:27:08.927Z]     Snapshot name: `Console logging Logs error level and above. 1`
[2020-04-22T17:27:08.927Z]
[2020-04-22T17:27:08.927Z]     Snapshot: "[error]: Testing simple message at error level... "
[2020-04-22T17:27:08.927Z]     Received: "[error]: Testing simple message at error level... "

From this result I cannot fathom what is wrong with the matcher. As far as I know, this is not a custom matcher. .log is declared as a TS string type.

As of right now I have no idea how to reproduce since the error has given me no indication of what is not matching.

Expected behavior

Output either matches and succeeds or provides a clear indication of how the matcher failed.

Link to repl or repo (highly encouraged)

No way to reproduce outside environment at the moment. No idea what is wrong because the error message is completely opaque.

envinfo

[2020-04-22T18:10:43.171Z] + npx envinfo --preset jest
[2020-04-22T18:10:44.515Z] npx: installed 1 in 1.119s
[2020-04-22T18:10:44.765Z] 
[2020-04-22T18:10:44.765Z]   System:
[2020-04-22T18:10:44.765Z]     OS: Linux 4.14 Alpine Linux
[2020-04-22T18:10:44.765Z]     CPU: (2) x64 Intel(R) Xeon(R) CPU E5-2676 v3 @ 2.40GHz
[2020-04-22T18:10:44.765Z]   Binaries:
[2020-04-22T18:10:44.765Z]     Node: 12.16.2 - /usr/local/bin/node
[2020-04-22T18:10:44.765Z]     Yarn: 1.22.4 - /usr/local/bin/yarn
[2020-04-22T18:10:44.765Z]     npm: 6.14.4 - /usr/local/bin/npm
[2020-04-22T18:10:44.765Z]   npmPackages:
[2020-04-22T18:10:44.765Z]     jest: ^25.4.0 => 25.4.0 
[2020-04-22T18:10:44.765Z]

[robross0606]

This turned out to be caused by Winston logger using os.EOL as the default for newlines. In this case, capturing and comparing snapshots on console output was failing due to an extra \r in the output that doesn’t show up on the error diff coming from Jest. Recommend an option to allow those diff messages to show escape codes. This was VERY hard to track down due to Jest output hiding control characters.

[SimenB]

Yeah exactly, that’s what concordance does