css/cssom/cssstyledeclaration-setter-attr.html

<!doctype html>
<title>CSSOM test: declaration block after setting via CSSOM</title>
<link rel="help" href="https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-setproperty">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
<script>
test(function() {
  let element = document.createElement("div");
  element.style.setProperty("doesntexist", "0");
  assert_false(element.hasAttribute("style"));
}, "Setting an invalid property via the declaration setter doesn't create a declaration");
test(function() {
  let element = document.createElement("div");
  element.style.setProperty("width", "-100");
  assert_false(element.hasAttribute("style"));
}, "Setting an invalid value via the declaration setter doesn't create a declaration");
</script>