chromium/third_party/blink/web_tests/editing/pasteboard/paste_match_style.html

<!doctype html>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script src="../assert_selection.js"></script>
<script>
test(() => {
    assert_not_equals(window.internals, undefined,
        'This test requires window.internals to access clipboard');

    assert_selection(
        '<div contenteditable>^b|</div>',
        selection => {
            selection.document.execCommand('cut');
            selection.document.execCommand('bold');
            selection.document.execCommand('insertText', false, 'a');
            selection.document.execCommand('pasteAndMatchStyle');
        },
        '<div contenteditable><b>ab|</b></div>',
        'Paste a letter into B');

    assert_selection(
        '<div contenteditable>^abc|</div>',
        selection => {
            selection.document.execCommand('cut');
            selection.document.execCommand('bold');
            selection.document.execCommand('pasteAndMatchStyle');
        },
        '<div contenteditable><b>abc|</b></div>',
        'Paste a word into B');
}, 'Pasting and matching style when there is nothing typed, but the typing style is set to bold.');
</script>