chromium/third_party/blink/web_tests/fast/forms/text-control-select-blurred.html

<div>Tests that setting selectionEnd on a blurred text control does not clobber selectionStart.</div>
<textarea>This is dummy text. This is dummy text.</textarea>
<input value="This is dummy text. This is dummy text">
<pre id="logger"></pre>
<script>
if (window.testRunner)
    testRunner.dumpAsText();

function assert(property, actual, expected)
{
    if (expected == actual)
        result = "PASS";
    else
        result = "FAIL: " + property + " was " + actual + " expected " + expected + ".";

    document.getElementById('logger').innerHTML += result + "\n";
}

function runTest(editArea)
{
    editArea.selectionStart = 10;
    editArea.blur();
    assert("selectionStart", editArea.selectionStart, 10);
    editArea.selectionEnd = 20;
    assert("selectionStart", editArea.selectionStart, 10);
    assert("selectionEnd", editArea.selectionEnd, 20);
}
runTest(document.querySelector('textarea'));
runTest(document.querySelector('input'));
</script>