support for asymmetricMatch as the value for toHaveAttribute matcher

[revathskumar]

Describe the feature you'd like:

Adding support for asymmetricMatchers like expec.stringContaining as the value to toHaveAttribute matcher
Eg:

      expect(getByLabelText(/Download Template/)).toHaveAttribute(
        "href",
        expect.stringContaining("?type=instruments")
      );

Suggested implementation:

Describe alternatives you've considered:

As of now this is achived by

      expect(getByLabelText(/Download Template/).getAttribute("href")).toEqual(
        expect.stringContaining("type=instruments")
      );

Teachability, Documentation, Adoption, Migration Strategy:

[gnapse]

I'm new to this asymmetric matchers thing. Thanks for bringing this up.

A couple of questions:

• What's the difference with enabling toHaveAttribute to receive a regex as the second argument? For example expect(element).toHaveAttribute('href', /type=instruments/).
• Wouldn't it be better if we decide to do this, to try to see if other matchers in this library can benefit from supporting these asymmetric matchers?

Also, I'm not sure I'll have time to tackle this if we accept supporting it. Would you be able to do it if so?

[revathskumar]

@gnapse Thanks for quick reply

I personally prefer asymmetricMatch to simple regex,

• to keep the api compatible with other expect matchers.
• dont want to complicate things by writing regexp instead of simple string
• negative lookup regex are nightmare, instead we can use expect.not.stringMatching()
• can use other methods like expect.anything(), expect.not.stringContaining(), expect.not.stringMatching()

expect support for Regex via expect.stringMatching.

I will give a try to add this during the weekend.

[gnapse]

Sounds good, that's quite a list of advantages you got there! Yes, please. I'm looking forward to learn how this works by seeing how you make it work with our matchers. Thanks!

PS: One thing I anticipate will need our attention at some point is TypeScript. The second argument to toHaveAttribute is now typed as string, and we'll need to be

string | WhateverTypeAsymmetricMatchersReturn

[gnapse]

🎉 This issue has been resolved in version 3.2.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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