chromium/src/third_party/blink/web_tests/fast/forms/number/number-spinbutton-state.html

<h1>BUG <a href="https://bugs.webkit.org/show_bug.cgi?id=79754">79754</a>[Forms] Spin button sometimes ignores Indeterminate of m_upDownState</h1>
<div id="outer">
<input id="num1" type="number" value="0">
</div>
<h2>Manualt test steps</h2>
<ol>
<li>Invoke browser with specifying screen position where moust pointer on the spin button.</li>
<li>Click left mouse button without moving mouse pointer.</li>
<li>Value should not be changed.</li>
</ol>
<h2>Result</h2>
<div id="logs"></div>
<script>
var logs = document.getElementById("logs");
function log(msg) { logs.innerHTML += msg + "<br>"; }

function testIt() {
    testRunner.dumpAsText();

    var outer = document.getElementById("outer");

    var num1 = document.getElementById("num1");
    var mouseX = num1.offsetLeft + num1.offsetWidth - 5;
    var mouseY = num1.offsetTop + 5;
    eventSender.mouseMoveTo(mouseX, mouseY);

    // Re-construct input element.
    var ctrlHtml = outer.innerHTML;
    outer.innerHTML = "";
    outer.innerHTML = ctrlHtml;

    var num2 = document.getElementById("num1");
    eventSender.mouseDown();
    log("expect 0, actual=" + num2.value);
    eventSender.mouseUp();

    // Move mouse pointer but still in spin button.
    eventSender.mouseMoveTo(mouseX, mouseY - 1);
    eventSender.mouseDown();
    log("expect 1, actual=" + num2.value);
}

if (window.testRunner) {
    testIt();
}
</script>