"You must provide a Promise to expect()" inconsistent between `resolves` and `rejects`

[0-CAT]

Describe the bug

If you call await expect(async () => { ... }).rejects.toThrow(), this will work as expected. However, change this to await expect(async () => { ... }).resolves.not.toThrow() and the test fails with the following error:

TypeError: You must provide a Promise to expect() when using .resolves, not 'function'.

This appears to just be an inconsistency between the two, based on the source code:

Seems like the Jest compatibility was not ported to .resolves but only to .rejects—looks like the bug is with that.

Reproduction

https://stackblitz.com/edit/vitest-dev-vitest-9omsvx?file=test%2Fbasic.test.ts

System Info

System:
    OS: macOS 15.1
    CPU: (10) arm64 Apple M2 Pro
    Memory: 98.27 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.15.0 - ~/.nvm/versions/node/v20.15.0/bin/node
    Yarn: 1.22.22 - /opt/homebrew/bin/yarn
    npm: 10.7.0 - ~/.nvm/versions/node/v20.15.0/bin/npm
    pnpm: 9.6.0 - /opt/homebrew/bin/pnpm
  Browsers:
    Safari: 18.1
  npmPackages:
    @vitest/coverage-v8: ^2.1.1 => 2.1.1
    @vitest/ui: ^2.1.1 => 2.1.1
    vitest: ^2.1.1 => 2.1.1

Used Package Manager

pnpm

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.
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• The provided reproduction is a minimal reproducible example of the bug.

[sheremet-va]

Seems like the Jest compatibility was not ported to .resolves but only to .rejects—looks like the bug is with that

Did you run the code in Jest to confirm this claim?

Vitest .resolves and .rejects API follows the Jest behavior. It doesn't accept a function in .resolves:

    Expected value   undefined
    Received:
      undefined
    
    Message:
      expect(received).resolves.not.toThrow()
    
    Matcher error: received value must be a promise
    
    Received has type:  function
    Received has value: [Function anonymous]

    Difference:

    Compared values have no visual difference

This appears to just be an inconsistency between the two, based on the source code

In the source you can see the comment // for jest compat - we support this behaviour for .rejects only because Jest supports it. And there is no such comment in .resolves because it's not supported by Jest.