Jest-dom: Could "it does not have its css property size(width/height) set to 0" be included in 'toBeVisible'?

[anyexinglu]

Describe the feature you'd like:

Sometimes, a div disappear with "transition: height 0.3s" (transition starts with height: 100px and ends with height: 0px)

Suggested implementation:

function isStyleHasNoSize(element) {
  const {getComputedStyle} = element.ownerDocument.defaultView

  const {width, height, display, visibility, opacity} = getComputedStyle(element)
  return (
    width !== '0px' && // and '0em', etc... ?
    width !== 0 &&
    height !== '0px' &&
    height !== 0 &&
  )
}

Describe alternatives you've considered:

I guess it's very difficult, even impossible, to include the rule into 'toBeVisible':
(1) A element with width: 0; height: 0; overflow: hidden may be visible:
<a href="#installation" style="width: 0; height: 0; overflow: hidden">Installation</a>

(2) A div with height: 0; width: 0; overflow: hidden; padding: 20px / height: 0; width: 0; overflow: hidden; border: 20px solid may also be visible:
<div style=" height: 0; width: 0; overflow: hidden; padding: 20px; ">Installation</div>
<div style=" height: 0; width: 0; overflow: hidden; border: 20px solid; ">Installation</div>

(3) A div with height: 0; width: 0; display: flex may also be visible:
<div style="height: 0; width: 0; display: flex">Installation</div>

Here toHaveStyle helps a little. (Although, we like toBeVisilbe since it's inherit, but toHaveStyle isn't )

[gnapse]

Why the double negation when you propose this? Isn't this the same as asking that having width or height set to zero should make toBeVisible return false?

Anyway, given you recognize some difficulties yourself with making it work, given all the special cases you've considered that still do not work. I can even imagine that there could be different behaviors in this regard between browsers.

I'd rather stick with what we've got, but I'm willing to leave the discussion open here.

[Archieru]

I'd also add overflow !== 'hidden' && to the list. WDYT?

[eps1lon]

TL;DR; toBeVisible should not be changed because a11y; toBeVisuallyHidden cannot be implemented correctly ins JSDOM and will add false positives to your tests. I'd recommend matching styles so that you see directly in your test what's happening.

The problem is that there are different kinds of visibility with regards to the accessibility tree. Zero width/height will still be included in the a11y tree.

From my experience these kind of elements are considered "visually hidden" not "invisible" which is used for e.g. skip links.

Another problem is that your approach is still incomplete. You would likely want to use something like offsetHeight which isn't implemented in JSDOM and therefore useless.

[anyexinglu]

@eps1lon you are right, I will close it