Testing expect(null).toMatchObject(...) against a Map or Set should fail #9522
Description
Describe the bug
The following tests should fail, but do not:
import { expect, test } from 'vitest'
test.fails('null does not match map', () => {
expect(null).toMatchObject(new Map([[1, 2]]));
})
test.fails('null does not match set', () => {
expect(null).toMatchObject(new Set([[1]]));
})Reproduction
https://stackblitz.com/edit/vitest-dev-vitest-y9khowyu?file=test%2Fbasic.test.ts
System Info
System:
OS: macOS 15.7.3
CPU: (14) arm64 Apple M4 Pro
Memory: 6.79 GB / 48.00 GB
Shell: 5.9 - /bin/zsh
Binaries:
Node: 25.2.1 - /opt/homebrew/bin/node
npm: 11.7.0 - /opt/homebrew/bin/npm
Browsers:
Firefox: 146.0
Firefox Nightly: 149.0a1
Safari: 18.6
npmPackages:
@vitejs/plugin-react: ^5.1.1 => 5.1.1
@vitest/coverage-v8: ^4.0.14 => 4.0.14
vitest: ^4.0.9 => 4.0.14Used Package Manager
npm
Validations
- Follow our Code of Conduct
- Read the Contributing Guidelines.
- Read the docs.
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- The provided reproduction is a minimal reproducible example of the bug.