chromium/third_party/blink/web_tests/external/wpt/shadow-dom/focus/text-selection-with-delegatesFocus.html

<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-actions.js"></script>
<script src="/resources/testdriver-vendor.js"></script>

<body>
    <x-shadow id="withoutFocus"></x-shadow>
    <x-shadow id="withFocus"></x-shadow>
</body>

<script>
'use strict';

/**
 * build shadow-root with delegates focus, a focusable element, and an (ideally) selectable text
 */
function buildShadowRootWithSelectableText( element, shouldDelegateFocus ) {
    element.attachShadow({ mode: 'open', delegatesFocus: shouldDelegateFocus });
    const span = document.createElement('span');
    span.textContent = 'Example Text to Select ';
    const button = document.createElement('button');
    button.textContent = 'Button';
    element.shadowRoot.append(span, button);
}

/**
 * command to select text in shadow-root
 */
function selectText(element, start, end) {
    getSelection().empty();
    const actions = new test_driver.Actions();
    actions.pointerMove(start, 0, {origin: element});
    actions.pointerDown();
    actions.pointerMove(end, 0, {origin: element});
    actions.pointerUp();
    return actions.send();
}

promise_test(async () => {
    const xShadow = document.getElementById('withoutFocus');
    buildShadowRootWithSelectableText(xShadow, false);

    // starting selection from the center of the element, and going right.
    // The important part here is that we start the selection in the center
    //   (where mouse-down events may be delegated)
    await selectText(xShadow, 0, 50)
    const s = getSelection();

    // because browsers may handle rendering differently, we can get different amounts of
    //   text selected, even when using the same start-end values. We opt in this case to
    //   verify just if any text is selected, since all we care about is if some text is
    //   selected.
    assert_greater_than(s.toString().length, 0);
}, 'shadow root has selectable text when focus is not delegated');

promise_test(async () => {
    const xShadow = document.getElementById('withFocus');
    buildShadowRootWithSelectableText(xShadow, true);

    await selectText(xShadow, 0, 50)
    const s = getSelection();

    assert_greater_than(s.toString().length, 0);
}, 'shadow root has selectable text when focus is delegated');

</script>