Tools/TestWebKitAPI/Tests/WebKitCocoa/web-authentication-get-assertion-hid-cancel.html

<input type="text" id="input">
<script>
    if (window.internals) {
        internals.setMockWebAuthenticationConfiguration({ silentFailure: true, hid: { expectCancel: true } });
        internals.withUserGesture(() => { input.focus(); });
    }

    const options = {
        publicKey: {
            challenge: new Uint8Array(16),
            timeout: 100
        }
    };

    navigator.credentials.get(options).then(credential => {
        // console.log("Succeeded!");
        window.webkit.messageHandlers.testHandler.postMessage("Succeeded!");
    }, error => {
        // console.log(error.message);
        window.webkit.messageHandlers.testHandler.postMessage(error.message);
    });
</script>