How to use ShouldThrowErrorIfNoElementIsFound method of PuppeteerSharp.Tests.QuerySelectorTests.PageQuerySelectorEvalTests class

I found a few issues in your code. First a few small errors in your javascript code: you don't need to async and an extra brackets.

var jsCode = @"() => {
  const element = document.querySelector('.productDetail svg[viewbox=""0 0 16 16""]');
  return window.getComputedStyle(element).getPropertyValue('color');
}";

Yarp Reverse proxy with Direct Forwarding is the answer:

Server code: (ASP.NET core minimal API):

Dictionary<string, string> routes = new();

app.UseRouting();
app.UseEndpoints(endpoints =>
{
    endpoints.Map("/connect/{**catch-all}", async httpContext =>
    {
        var route = httpContext.Request.GetDisplayUrl();

        await app.Services.GetRequiredService<IHttpForwarder>().SendAsync(
            httpContext,
            routes.TryGetValue(Path.GetFileName(new Uri(route).AbsolutePath), out string targetRoute) ? targetRoute : route,
            new HttpMessageInvoker(new SocketsHttpHandler()
            {
                UseProxy = false,
                AllowAutoRedirect = false,
                AutomaticDecompression = DecompressionMethods.None,
                UseCookies = false,
                ActivityHeadersPropagator = new ReverseProxyPropagator(DistributedContextPropagator.Current)
            })
        );
    });
});

app.MapGet("/", async () =>
{
    var b = await Puppeteer.LaunchAsync(new()
    {
        ExecutablePath = browserPath // set your chrome directory
    });

    var id = Path.GetFileName(b.WebSocketEndpoint);

    routes.Add(id, b.WebSocketEndpoint);

    return $"ws://your-server-ip-address/connect/{id}";
});

app.Run();

Client code:

await Puppeteer.ConnectAsync(new() { BrowserWSEndpoint = await httpClient.GetStringAsync("http://your-server-ip-address") })

You can use different browser instances for each logical instances. I mean instead of trying to set different proxy for each page/tab with different proxy just create new browser instance and set proxy via launch args.

If this solution doesn't fit your needs, check this question. There is library for NodeJS which give ability to use different proxy per each page/tab. You can check that library source code and implement same things inside your C# application.

That library is using very simple method. Instead of sending requests via puppeter's browser/page library send request via nodejs http tools. It can be done by using method page.setRequestInterception. So library intercept each request from page, after that gather data and send request via http tools. I used C# a long time ago. So maybe I am wrong, but you can try to use HttpWebRequest or something similar. After you get result you should use method request.respond and pass response results there. In this way you can put any kind of proxy inside your application. Check here code of library.

You should use EvaluateExpressionAsync.

_page.EvaluateExpressionAsync("JSON.stringify(performance.timeOrigin)").ConfigureAwait(false);

I think you will find easy to translate the code from puppeteer recorder to Puppeteer-Sharp. At least you can get the selectors from there.

Once you have those selectors you could do 3 things:

One option is setting a directory where the browser can store the cookies using the UserDataDir property. You could open the browser BrowserFetcher downloads and click that button.

A better solution is executing a script using EvaluateFunctionAsync to check if you have the cookies button and click it (using the selector you got from the recorder). Your code will be more flexible.

Last option would be downloading Chromie 77 or higher and launch it using ExecutablePath.

Yarp Reverse proxy with Direct Forwarding is the answer:

Server code: (ASP.NET core minimal API):

Dictionary<string, string> routes = new();

app.UseRouting();
app.UseEndpoints(endpoints =>
{
    endpoints.Map("/connect/{**catch-all}", async httpContext =>
    {
        var route = httpContext.Request.GetDisplayUrl();

        await app.Services.GetRequiredService<IHttpForwarder>().SendAsync(
            httpContext,
            routes.TryGetValue(Path.GetFileName(new Uri(route).AbsolutePath), out string targetRoute) ? targetRoute : route,
            new HttpMessageInvoker(new SocketsHttpHandler()
            {
                UseProxy = false,
                AllowAutoRedirect = false,
                AutomaticDecompression = DecompressionMethods.None,
                UseCookies = false,
                ActivityHeadersPropagator = new ReverseProxyPropagator(DistributedContextPropagator.Current)
            })
        );
    });
});

app.MapGet("/", async () =>
{
    var b = await Puppeteer.LaunchAsync(new()
    {
        ExecutablePath = browserPath // set your chrome directory
    });

    var id = Path.GetFileName(b.WebSocketEndpoint);

    routes.Add(id, b.WebSocketEndpoint);

    return $"ws://your-server-ip-address/connect/{id}";
});

app.Run();

Client code:

await Puppeteer.ConnectAsync(new() { BrowserWSEndpoint = await httpClient.GetStringAsync("http://your-server-ip-address") })

I solved the problem like this.

const links = await page.evaluate(() =>
              Array.from(document.querySelectorAll('a span'), e => 
              e.textContent));

PuppeteerSharp doesn't have those APIs (because Pupppeteer doesn't have them). But, you could try sending those messages to the browser in the same way TapAsync does.

This is the TapAsync code:

// Touches appear to be lost during the first frame after navigation.
// This waits a frame before sending the tap.
// @see https://crbug.com/613219
await _client.SendAsync("Runtime.evaluate", new RuntimeEvaluateRequest
{
    Expression = "new Promise(x => requestAnimationFrame(() => requestAnimationFrame(x)))",
    AwaitPromise = true
}).ConfigureAwait(false);

var touchPoints = new[] { new TouchPoint { X = Math.Round(x), Y = Math.Round(y) } };
await _client.SendAsync("Input.dispatchTouchEvent", new InputDispatchTouchEventRequest
{
    Type = "touchStart",
    TouchPoints = touchPoints,
    Modifiers = _keyboard.Modifiers
}).ConfigureAwait(false);

await _client.SendAsync("Input.dispatchTouchEvent", new InputDispatchTouchEventRequest
{
    Type = "touchEnd",
    TouchPoints = Array.Empty<TouchPoint>(),
    Modifiers = _keyboard.Modifiers
}).ConfigureAwait(false);

Page has a public property Client. You can use that Client to perform these calls.

As you can check here, Type supports: touchStart, touchEnd, touchMove and touchCancel.

This works for me:

var alertMessage = "";
//attach to page during entire page life-cycle (until closed).
//handles the case where an javscript alert comes up during login.
page.Dialog += new EventHandler<DialogEventArgs>(async (sender, args) =>
{
    alertMessage = args.Dialog.Message;
    await args.Dialog.Accept(); //this closes it..
    Log.Information("Popup squashed in Login(): {0}", alertMessage);
    Thread.Sleep(500);
});