Implement toBeInvalid & toBeValid matchers

[hiwelo]

What:

This pull-request is a proposed implementation for the custom matchers toBeInvalid and toBeValid.

Why:

This is following a discussion we quickly had with the issue #108.
These two custom matchers can avoid folks to check with different expect tests:

• is having aria-invalid not equal to false
• checkValidity is returning false

How:

• toBeInvalid checks if one of these are correct:

  • aria-invalid exists and if the value is not equal to false (as each value different than false are considered true (ref))

  • the targetted element is a form element and checkValidity() returns false

• toBeValid checks if all of these are correct:

  • aria-invalid is not part of the markup or the value is equal to false

  • if the targetted element is a form element, checkValidity() returns true

Checklist:

• Documentation
• Tests
• Updated Type Definitions
• Ready to be merged
• Added myself to contributors table

I do not know if it's a good practice, please let me know your thoughts about that: I had to use jsdom to be able to test if these two custom matchers are correctly checking .checkValidity().
Without it, .checkValidity() was always returning true even when the input had an invalid value.

[gnapse]

Looking great. Just a couple of comments requesting to add more documentation or links to documentation and issues.

[hiwelo]

I added linked resources to the README.md.
I will move the extract the jsdom object within an helper function and let's see after what we can do with this.

I will at least document why it's there.
Also, it should only impact the tests, not the usage of jest-dom itself. At the moment, it is a devDependency only called within this test file.
In the toBeInvalid file, any real DOM node should work, no need for this library when using jest-dom. 👍

[hiwelo]

Ok, so finally I was able to remove the specific testing I created earlier.
Thanks to the jsdom update to a 15+ version, I was able to checkValidaty() on a rendered HTMLElement using the existing helper. 🎉
Way cleaner this way 🙂

Every test passed, so I think the upgrade should not be an issue.

[hiwelo]

Hmm… The test is completed without any issue on my local machine… :/
Any idea why it's failing specifically on Travis?

[gnapse]

Hmm… The test is completed without any issue on my local machine… :/
Any idea why it's failing specifically on Travis?

It seems the jsdom issue is still biting us

I don't mind if you need to revert this to how it was for the time being.

[hiwelo]

Cool! I will revert my last commit and push it again.

[hiwelo]

@gnapse I just rebased the branch to remove the last commit 👍
(gosh, I love git rebase so much haha)

[gnapse]

🎉 This PR is included in version 3.4.0 🎉

The release is available on:

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

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