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chromium/third_party/blink/web_tests/external/wpt/infrastructure/testdriver/click.html 

<!DOCTYPE html>
<meta charset="utf-8">
<title>TestDriver click method</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>

<button type="button" id="button">Button</button>

<script>
async_test(t => {
  let button = document.getElementById("button");
  test_driver
    .click(button)
    .then(() => t.done())
    .catch(t.unreached_func("click failed"));
});
</script>