chromium/third_party/blink/web_tests/external/wpt/html/semantics/document-metadata/the-style-element/style_type_change.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Dynamically changing HTMLStyleElement.type should change the rendering accordingly</title>
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
    <link rel="help" href="https://html.spec.whatwg.org/multipage/#the-style-element">
    <style type="no/mime">
      body { color: green }
    </style>
  </head>
  <body>
    Text content.
    <script>
      var style = document.querySelector("style");
      test(function() {
        assert_equals(document.styleSheets.length, 0);
      }, "Check initial styleSheets length type");

      test(function() {
        assert_not_equals(getComputedStyle(document.querySelector("body")).color, "rgb(0, 128, 0)");
        assert_equals(document.styleSheets.length, 0);
        style.type = "text/css";
        assert_equals(getComputedStyle(document.querySelector("body")).color, "rgb(0, 128, 0)");
        assert_equals(document.styleSheets.length, 1);
      }, "Change type from invalid type to valid type");

      test(function() {
        assert_equals(getComputedStyle(document.querySelector("body")).color, "rgb(0, 128, 0)");
        assert_equals(document.styleSheets.length, 1);
        style.type = "no/mime";
        assert_not_equals(getComputedStyle(document.querySelector("body")).color, "rgb(0, 128, 0)");
        assert_equals(document.styleSheets.length, 0);
      }, "Change type from valid type to invalid type");

    </script>
  </body>
</html>