<!doctype html>
<html>
    <head>
        <meta charset="utf-8">
        <title>Testing new callback</title>
        <script src="/resources/testharness.js"></script>
        <script src="/resources/testharnessreport.js"></script>
    </head>
    <body>
        <script>
function waitFor(duration)
{
    return new Promise((resolve) => setTimeout(resolve, duration));
}

function withFrame(url)
{
    return new Promise((resolve) => {
        let frame = document.createElement('iframe');
        frame.src = url;
        frame.onload = function() { resolve(frame); };
        document.body.appendChild(frame);
    });
}

async function verifyUserScriptInjectedCount(expected)
{
    let counter = 0;
    while (++counter < 100) {
        if (testRunner.userScriptInjectedCount === expected)
            return;
        await waitFor(10);
    }
    return Promise.reject("Did not get expected value " + expected + " but " + testRunner.userScriptInjectedCount);
}

promise_test(async () => {
    if (!window.testRunner) {
        reject("Test requires internals API");
        return;
    }
    assert_equals(testRunner.userScriptInjectedCount, 0);
    testRunner.injectUserScript("function a() { }");

    await withFrame(".");
    await verifyUserScriptInjectedCount(1);

    await withFrame(".");
    await verifyUserScriptInjectedCount(2);
}, 'Test willInjectUserScript callback being called');
        </script>
    </body>
</html>