chromium/third_party/blink/web_tests/editing/pasteboard/paste-placeholder-input.html

<!DOCTYPE html>
<html>
<head>
    <title>Test -webkit-user-select with a placeholder in a textfield.</title>
    <script src="../../resources/js-test.js"></script>
    <style>
    * { -webkit-user-select: none; }
    input { -webkit-user-select: text; }
    </style>
</head>
<body>
    <p id="description"></p>
    <div id="console"></div>
    <input id="x" value="PASS">
    <script>
    description("Test that deleting the text in a textfield, and pasting, doesn't hit an issue with -webkit-user-select on br");

    var input = document.getElementById("x");
    input.focus();
    input.select();

    document.execCommand("Copy");
    document.execCommand("Delete");
    document.execCommand("Paste");

    shouldBe('input.value', '"PASS"');

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