LayoutTests/editing/inserting/insert-paragraph-in-designmode-document.html

<!DOCTYPE html>
<html>
<head>
    <script src="../../resources/dump-as-markup.js"></script>
    <script>
        addEventListener("DOMContentLoaded", () => {
            document.designMode = "on";

            const container = document.querySelector(".container");
            getSelection().setPosition(container.childNodes[0], 6);
            document.execCommand("InsertParagraph");
            document.querySelectorAll("script").forEach(script => script.remove());
            Markup.description("Verifies that after inserting a newline after a period doesn't insert an extra space in front of the newly inserted line.");
            Markup.dump("document.body");
        });
    </script>
</head>
<body>
    <div class="container">Hello.This is a test.</div>
</body>
</html>