chromium/third_party/blink/web_tests/fast/css/focus-visible-setting.html

<!DOCTYPE html>
<html>
<head>
  <title>CSS Test (Selectors): "Always show focus" preference causes :focus-visible to always match</title>
  <script src="../../resources/testharness.js"></script>
  <script src="../../resources/testharnessreport.js"></script>
  <style>
    :focus-visible {
      outline: darkgreen dotted 1px; /* fallback for Edge */
      outline: darkgreen auto 5px;
    }

    :focus:not(:focus-visible) {
      outline-color: darkred;
      background-color: darkred;
    }
  </style>
</head>
<body>
  <div id="el" tabindex="0">Focus me.</div>
  <script>
    function clickOn(element) {
      return new Promise(function(resolve, reject) {
        if (!window.eventSender)
          return reject();

        var rect = element.getBoundingClientRect();
        var x = rect.left + (rect.width / 2);
        var y = rect.top + (rect.height / 2);
        var pointerActions = [{
          source: "mouse",
          actions: [
              { name: "pointerMove", x: x, y: y },
              { name: "pointerDown", x: x, y: y, button: 0 },
              { name: "pointerUp", x: x, y: y, button: 0 },
              { name: "pointerMove", x: 0, y: 0 }
          ]
        }];
        chrome.gpuBenchmarking.pointerActionSequence(pointerActions, resolve);
      });
    }

    async_test(function(t) {
      el.addEventListener("focus", t.step_func(function() {
        assert_equals(getComputedStyle(el).outlineColor, "rgb(139, 0, 0)");
        internals.settings.setAccessibilityAlwaysShowFocus(true);
        // changing the setting should trigger style recalc
        assert_equals(getComputedStyle(el).outlineColor, "rgb(0, 100, 0)");
      }), true);

      // Click the div; without the setting, this would not trigger :focus-visible matching
      clickOn(el)
        .then(t.step_func(() => {
          t.done();
        })).catch(t.step_func((reason) => {
          assert_true(false, reason);
          t.done();
        }));
    }, ":focus-visible always matches if the 'always show focus' setting is enabled.");
  </script>
</body>
</html>