WaitForNavigationAsync should resolve if Frame already has requested lifecycle

I expect that calling:

await page.WaitForNavigationAsync();

would resolve immediately if the page have already collected ‘load’ lifecycle event before. Also, I expect the following sequence should complete successfully instead of hanging forever as it does currently with version 5.1.0 of puppeteer-sharp:

await page.GoToAsync(url, WaitUntilNavigation.DOMContentLoaded);
await page.WaitForNavigationAsync();

As a workaround for my project I slightly modified FrameManager.cs lines 149-164 to be:

        public async Task<Response> WaitForFrameNavigationAsync(Frame frame, NavigationOptions options = null)
        {
            var timeout = options?.Timeout ?? TimeoutSettings.NavigationTimeout;
            using (var watcher = new LifecycleWatcher(this, frame, options?.WaitUntil, timeout))
            {
                var raceTask = await Task.WhenAny(
                    watcher.NewDocumentNavigationTask,
                    watcher.SameDocumentNavigationTask,
                    watcher.LifecycleTask, // <-- add this line to resolve lifecycle events without waiting for actual navigation
                    watcher.TimeoutOrTerminationTask).ConfigureAwait(false);

                await raceTask.ConfigureAwait(false);

                return watcher.NavigationResponse;
            }
        }

Please check if it may be acceptable fix for public, or maybe a separate method for waiting for lifecycle events without doing actual navigation should be added.

[kblok]

The most common pattern is doing something like this:

await Task.WhenAll(
    Page.ClickAsync("a"),
    Page.WaitForNavigationAsync());

I think that with the change you’re suggesting, WaitForNavigationAsync will immediately be resolved, breaking that pattern.

[igristov]

High chances you can reproduce the issue with this simple test:

class Program
{
    static async Task Main(string[] args)
    {
        await new BrowserFetcher().DownloadAsync();
        await using var browser = await Puppeteer.LaunchAsync(new LaunchOptions { Headless = false });
        var sites = new[] { "news.yahoo.com", "news.google.com", "cnn.com", "wsj.com", "news.bbc.co.uk", "latimes.com" };
        Task.WaitAll(sites.Select(x => Test(browser, "https://" + x)).ToArray());
    }
    static async Task Test(Browser browser, string url)
    {
        await using var page = await browser.NewPageAsync();
        await page.SetRequestInterceptionAsync(true);
        page.Request += async (s, e) => await e.Request.ContinueAsync();
        page.DOMContentLoaded += (s, e) => Debug.WriteLine($"DOMContentLoaded {page.Url} [{url}]");
        page.Load += (s, e) => Debug.WriteLine($"Load {page.Url} [{url}]");
        await page.GoToAsync(url);
    }
}

You’ll catch all DOMContentloaded but only few Load events…