css/css-pseudo/pseudo-replaced-elements.html

<!doctype html>
<meta charset="utf-8">
<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
<link rel="author" href="https://mozilla.org" title="Mozilla">
<link rel="help" href="https://issues.chromium.org/issues/365052666">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1911253">
<link rel="help" href="https://drafts.csswg.org/css-pseudo/#generated-content">
<!--
  https://drafts.csswg.org/css-pseudo/#generated-content:
     Also as with regular child elements, the ::before and ::after pseudo-elements
     are suppressed when their parent, the originating element, is replaced.
-->
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<title>Replaced elements don't generate before / after CSS pseudo-elements</title>
<style>
  input::before,
  video::before,
  progress::before {
    content: "X";
    display: block;
    /* Not resolvable if box is not generated */
    width: 10%;
  }
  span {
    display: block;
    /* Not resolvable if box is not generated */
    width: 10%;
  }
</style>
<input type=text>
<input type=date>
<input type=time>
<input type=datetime-local>
<input type=checkbox>
<input type=radio>
<input type=file>
<input type=range>
<input type=color>
<input type=hidden>
<input type=search>
<video controls></video>
<video></video>
<progress></progress>
<!-- These are special since they are no longer replaced with appearance: none -->
<input style="appearance: none" type=checkbox>
<input style="appearance: none" type=radio>
<!-- These are not special -->
<input style="appearance: none" type=text>
<input style="appearance: none" type=date>
<input style="appearance: none" type=time>
<input style="appearance: none" type=datetime-local>
<input style="appearance: none" type=file>
<input style="appearance: none" type=range>
<input style="appearance: none" type=color>
<input style="appearance: none" type=hidden>
<input style="appearance: none" type=search>
<progress></progress>
<script>
for (let element of document.querySelectorAll("input, video")) {
  test(function() {
    const child = element.appendChild(document.createElement("span"));
    const childWidth = getComputedStyle(child).width;
    const hasChildBox = childWidth.endsWith("px");

    const pseudoWidth = getComputedStyle(element, "::before").width;
    const hasPseudoBox = pseudoWidth.endsWith("px");

    assert_equals(hasChildBox, hasPseudoBox, "Should only generate a box for pseudo-elements if it generates a box for child elements");
    if (hasChildBox || hasPseudoBox) {
      assert_equals(childWidth, pseudoWidth, "Child and pseudo sizes should match");
    }
    const expectedBox = element.style.appearance == "none" && (element.type == "checkbox" || element.type == "radio");
    assert_equals(hasPseudoBox, expectedBox, "Should only generate a box for appearance: none checkboxes/radio buttons");
  }, `${element.tagName} ${element.style.cssText} ${element.type || element.controls || ""}`);
}
</script>