vitest-dev / vitest-dev/vitest
Snapshots incorrectly treat CR as LF
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Description
Describe the bug
Vitest treats CRLF and LF as the same in snapshots which leads to the wrong snapshot being used. E.g. if a string has CRLF it'll incorrectly be normalised to LF.
import {test, expect} from 'vitest';
test.for([
'a\nb', // ["a", "\n", "b"], snapshot will have ["a", "\n", "b"]
'a\r\nb', // ["a", "\r", "\n", "b"], snapshot will have ["a", "\n", "\n", "b"]
])('"%s".split("")', (input) => {
expect(input.split("")).toMatchSnapshot();
})
On Windows it correctly generates two snapshots for both. But then when it compares the snapshot on a second run this test will fail because the line endings aren't right.
On Ubuntu it writes the first snapshot to the file. Then it incorrectly uses the first snapshot for the second test and fails.
Reproduction
https://github.com/melusc/vitest-snapshot-crlf
You can see how it behaves on Windows or Ubuntu in the Github Actions logs: https://github.com/melusc/vitest-snapshot-crlf/actions/runs/17612890884
System Info
System:
OS: Windows 11 10.0.26100
CPU: (8) x64 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz
Memory: 770.81 MB / 7.84 GB
Binaries:
Node: 23.6.0 - C:\nvm4w\nodejs\node.EXE
Yarn: 4.6.0 - C:\nvm4w\nodejs\yarn.CMD
npm: 10.9.2 - C:\nvm4w\nodejs\npm.CMD
Browsers:
Edge: Chromium (124.0.2478.105)
npmPackages:
vitest: ^3.0.2 => 3.0.2
Used Package Manager
yarn
Validations
- Follow our Code of Conduct
- Read the Contributing Guidelines.
- Read the docs.
- Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
- Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
- The provided reproduction is a minimal reproducible example of the bug.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the linked minimal reproduction with Vitest on Windows and Ubuntu, then compare the generated and second-run snapshot behavior described in the issue. Done means CRLF and LF remain distinct in snapshots and the reproduction passes consistently across both environments.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- testing-qa
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100