vitest-dev / vitest-dev/vitest
`ExpectationResult` of a custom asymmetric matcher is ignored
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- TypeScript
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Description
Describe the bug
When I have a custom asymmetric matcher, Vitest applies it correctly but disregards the matcher's ExpectationResult properties like message, actual, and expected if the matcher fails. I expect the inverse assertions (.not) to have the same problem.
Reproduction
Here's a sandbox: https://stackblitz.com/edit/vitest-dev-vitest-je43znvc?file=vite.config.ts,vitest.setup.ts,test%2Fbasic.test.ts&initialPath=__vitest__/
System Info
Irrelevant.
Used Package Manager
npm
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 with the linked StackBlitz reproduction, especially vite.config.ts, vitest.setup.ts, and test/basic.test.ts, and run the failing custom asymmetric matcher case. Trace how the matcher’s ExpectationResult is handled on failure and verify that message, actual, and expected are preserved for both normal and inverse assertions.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- testing
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 56/100