How to use EvaluateHandleAsync method of Microsoft.Playwright.Core.Locator class

Using ideas from comments on my answer I was able to accomplish the goal. I ended up passing a cancellation token to a Task.Delay(30000, token). Then if I got the data I wanted and set the result value, I just cancelled the token.

string? result = null;
var tokenSource = new CancellationTokenSource();
var cancelToken = tokenSource.Token;

// Start listening for new pages (ClickAsync below opens in a new page)
context.Page += (_, newPage) =>
{
  // From the new page, start listening for requests that page generates
  newPage.Request += async (_, request) =>
  {
    if (request.Url.Contains("some_identifier"))
    {
      await newPage.GotoAsync(request.Url);
      result = await newPage.InnerTextAsync("body");
      tokenSource.Cancel(); // <-- Got what we needed, cancel 30 second timer
    }
  };
};

await mainPage.Locator("a#somelink").ClickAsync();

try {
  await Task.Delay(30000, cancelToken); // <-- Timeout after 30 seconds.
}
catch
{
  // Not a fan of tokenSource.Cancel() throwing an exception, but I can deal with it.
}

return result;

What I've done is add a runsettings file to visual studio called, for example, test.runsettings with the following content:

<?xml version="1.0" encoding="utf-8"?>
<RunSettings>
  <RunConfiguration>
    <EnvironmentVariables>
        <HEADED>1</HEADED>
    </EnvironmentVariables>
  </RunConfiguration>
</RunSettings>

Then, as long as VS chooses that runsettings file (see Test > Configure Run Settings in the menu) you should start getting HEADED mode

The error came from me not correctly understanding Docker stages. Here a fixed Dockerfile, where I installed Playwright in the base stage:

FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS base
RUN apt-get update
RUN apt-get -y install curl gnupg
RUN curl -sL https://deb.nodesource.com/setup_16.x  | bash -
RUN apt-get -y install nodejs
RUN npx playwright install
RUN apt-get update && apt-get install -y --no-install-recommends \
    fonts-liberation\
    libasound2\
    libatk-bridge2.0-0\
    libatk1.0-0\
    libatspi2.0-0\
    libcairo2\
    libcups2\
    libdbus-1-3\
    libdrm2\
    libgbm1\
    libglib2.0-0\
    libgtk-3-0\
    libnspr4\
    libnss3\
    libpango-1.0-0\
    libx11-6\
    libxcb1\
    libxcomposite1\
    libxdamage1\
    libxext6\
    libxfixes3\
    libxrandr2
WORKDIR /app

FROM mcr.microsoft.com/dotnet/sdk:6.0-focal  AS build
WORKDIR /src
COPY ["Dashboard/Dashboard.csproj", "Dashboard/"]
RUN dotnet restore "Dashboard/Dashboard.csproj"
COPY . .
WORKDIR "/src/Dashboard"
RUN dotnet build "Dashboard.csproj" -c Release -o /app/build
FROM build AS publish
RUN dotnet publish "Dashboard.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "Dashboard.dll"]

I ended up raising a bug and it seems others had the same issue

https://github.com/microsoft/playwright-dotnet/issues/1841

I hit the same issue recently.

1. The error you are getting means that the certificates presented by the moon server to your client is incomplete. Try to provide the full chain of certs there!
2. If later, you get the "WebSocket error: self signed certificate in certificate chain" then you need to set the NODE_EXTRA_CA_CERTS env variable pointing at your pem file. This is happening being Node cannot read the trusted CAs by default.

This is the question/solution I posted for the Playwright team along with the resolution.

# Install the CLI once.
dotnet tool install --global Microsoft.Playwright.CLI
# Install the browsers
playwright install

(The current error description is a bug in 1.14, it gets fixed with 1.15.)

Finally I was able to find a way to run the tests inside a Docker container using a custom image. Here is what I've done:

FROM mcr.microsoft.com/dotnet/sdk:5.0.404-focal AS build
WORKDIR /src
COPY ["PlaywrightSharp/PlaywrightSharp.csproj", "PlaywrightSharp/"]
RUN dotnet restore "PlaywrightSharp/PlaywrightSharp.csproj"

COPY . .
WORKDIR "/src/PlaywrightSharp"

RUN apt-get update -yq && apt-get upgrade -yq && apt-get install -yq curl git nano
RUN curl -sL https://deb.nodesource.com/setup_16.x | bash - && apt-get install -yq nodejs build-essential
RUN npm install -g npm

RUN apt-get install -y wget xvfb unzip

# Set up the Chrome PPA
RUN wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add -
RUN echo "deb http://dl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google.list

# Update the package list and install chrome
RUN apt-get update -y
RUN apt-get install -y google-chrome-stable
RUN apt-get install -y firefox

#RUN dotnet add package Microsoft.Playwright
RUN dotnet build "PlaywrightSharp.csproj" -c Release -o /app/build
RUN npx playwright install-deps
RUN npx playwright install


FROM build AS testrunner
WORKDIR "/src/PlaywrightSharp"
CMD ["dotnet", "test", "--no-restore", "--settings:Firefox.runsettings", "--logger:trx"]

It looks like npx playwright install-deps was not enough to run the tests and I had to install Chrome and Firefox also.

I hit the same issue recently.

1. The error you are getting means that the certificates presented by the moon server to your client is incomplete. Try to provide the full chain of certs there!
2. If later, you get the "WebSocket error: self signed certificate in certificate chain" then you need to set the NODE_EXTRA_CA_CERTS env variable pointing at your pem file. This is happening being Node cannot read the trusted CAs by default.

This is the question/solution I posted for the Playwright team along with the resolution.

So I resolved this with the following logic.

I created two variables:

1. List<string> downloadedFiles = new List<string>();
2. List<string> fileDownloadSession = new();

I then created a method to add as a handler to the page.Download that looks like this:

private async void downloadHandler(object sender, IDownload download)
{
    fileDownloadSession.Add("Downloading...");
    var waiter = await download.PathAsync();
    downloadedFiles.Add(waiter);
    fileDownloadSession.Remove(fileDownloadSession.First());
}

Afterwards, I created a public method to get the downloaded files that looks like this:

public List<string> GetDownloadedFiles()
{
    while (fileDownloadSession.Any())
    {
        
    }
    
    var downloadedFilesList = downloadedFiles;
    downloadedFiles = new List<string>();
    return downloadedFilesList;
}

All these methods and planning are in a separate class of their own so that they can monitor the downloaded files properly, and also to freeze the main thread so it can grab all of the required files.

All in all it seems just as sketchy of a solution, similarly to how you would implement it in Selenium, nothing much has changed in terms of junkyard implementations in the new frameworks.

You can find my custom class here: https://paste.mod.gg/rztmzncvtagi/0, enjoy, there is no other topic that answers this specific question for playwright on C#.

Code here, in case it gets deleted from paste.mod.gg:

using System.Net;
using System.Runtime.InteropServices.JavaScript;
using Flanium;
using FlaUI.UIA3;
using Microsoft.Playwright;
using MoreLinq;
using Polly;

namespace Fight;

public class WebBrowser
{
    private IBrowser _browser;
    private IBrowserContext _context;
    private IPage _page;
    private bool _force;
    private List<string> downloadedFiles = new List<string>();
    private List<string> fileDownloadSession = new();

    public void EagerMode()
    {
        _force = true;
    }
    
    public enum BrowserType
    {
        None,
        Chrome,
        Firefox,
    }

    public IPage GetPage()
    {
        return _page;
    }
    public WebBrowser(BrowserType browserType = BrowserType.Chrome, bool headlessMode = false)
    {
        var playwright = Playwright.CreateAsync().Result;

        _browser = browserType switch
        {
            BrowserType.Chrome => playwright.Chromium.LaunchAsync(new BrowserTypeLaunchOptions {Headless = headlessMode}).Result,
            BrowserType.Firefox => playwright.Firefox.LaunchAsync(new BrowserTypeLaunchOptions {Headless = headlessMode}).Result,
            _ => null
        };

        _context = _browser.NewContextAsync().Result;
        _page = _context.NewPageAsync().Result;
        _page.Download += downloadHandler;
        
        Console.WriteLine("WebBrowser was successfully started.");
    }

    private async void downloadHandler(object sender, IDownload download)
    {
        fileDownloadSession.Add("Downloading...");
        var waiter = await download.PathAsync();
        downloadedFiles.Add(waiter);
        fileDownloadSession.Remove(fileDownloadSession.First());
    }
    
    public List<string> GetDownloadedFiles()
    {
        while (fileDownloadSession.Any())
        {
            
        }
        
        var downloadedFilesList = downloadedFiles;
        downloadedFiles = new List<string>();
        return downloadedFilesList;
    }
    
    
    public void Navigate(string url)
    {
        _page.GotoAsync(url).Wait();
    }

    public void Close(string containedURL)
    {
        var pages = _context.Pages.Where(x => x.Url.Contains(containedURL));
        if (pages.Any())
            pages.ForEach(x => x.CloseAsync().Wait());
    }





    public IElementHandle Click(string selector, int retries = 15, int retryInterval = 1)
    {
        var element = Policy.HandleResult<IElementHandle>(result => result == null)
            .WaitAndRetry(retries, interval => TimeSpan.FromSeconds(retryInterval))
            .Execute(() =>
            {
                var element = FindElement(selector);
                if (element != null)
                {
                    try
                    {
                        element.ClickAsync(new ElementHandleClickOptions() {Force = _force}).Wait();
                        element.DisposeAsync();
                        return element;
                    }
                    catch (Exception e)
                    {
                        return null;
                    }
                }

                return null;
            });
        
        return element;
    }

    public IElementHandle FindElement(string selector)
    {
        IElementHandle element = null;

        var Pages = _context.Pages.ToArray();

        foreach (var w in Pages)
        {
            //============================================================
            element = w.QuerySelectorAsync(selector).Result;
    

    if (element != null)
        {
            return element;
        }

        //============================================================
        var iframes = w.Frames.ToList();
        var index = 0;

        for (; index < iframes.Count; index++)
        {
            var frame = iframes[index];

            
            element = frame.QuerySelectorAsync(selector).Result;
            if (element is not null)
            {
                return element;
            }

            var children = frame.ChildFrames;

            if (children.Count > 0 && iframes.Any(x => children.Any(y => y.Equals(x))) == false)
            {
                iframes.InsertRange(index + 1, children);
                index--;
            }
        }
    }

    return element;
}
}