Web

WebEngine drives Chromium through Microsoft.Playwright. The first launch in a process installs the headless shell, so the first run needs network access. Set E2E_SKIP_BROWSER_INSTALL=1 when the browser is already installed.

1. Create the test project

dotnet new nunit -n MyApp.E2ETests
cd MyApp.E2ETests
dotnet add package E2E
dotnet add package E2E.NUnit          # or E2E.XUnit.V3 for xUnit v3

Add E2E to the implicit usings, so tests need no using E2E;:

<ItemGroup>
  <Using Include="E2E" />
  <Using Include="NUnit.Framework" />
</ItemGroup>

2. Point at your app

{
  "targets": [{ "name": "web", "platform": "web", "app": { "url": "http://localhost:3000" } }],
  "actionTimeout": 15000,
  "assertionTimeout": 10000,
  "agents": {
    "default": {
      "provider": "copilot",
      "model": "claude-sonnet-5.5",
      "context": "MyApp is a project tracker. Never delete data."
    }
  },
  "cache": { "dir": ".e2e/cache" }
}

Copy the file to the output folder:

<ItemGroup>
  <None Update="e2e.config.json" CopyToOutputDirectory="PreserveNewest" />
</ItemGroup>

Start your app at that address before the run. App.OpenAsync("/path") opens a path on app.url.

3. Write a test

The steps below are placeholders for a signup flow. Replace the headings, goals, and checks with your own app’s. To run a finished web test right away, use the Dariten sample.

Derive from E2ETest. It starts a WebEngine session for each test.

using E2E.NUnit;

public sealed class SignupTests : E2ETest
{
    [Test]
    public async Task The_home_page_opens()
    {
        await App.OpenAsync("/");
        await Expect.That(Screen.GetByRole("heading", "Welcome")).ToBeVisibleAsync();
    }

    [Test]
    [Category("RealModel")]
    public async Task A_visitor_signs_up_for_a_trial()
    {
        await App.OpenAsync("/");

        await Agent.ActAsync("sign up for a free trial as {name} with email {email}", new ActOptions
        {
            Params = new Dictionary<string, object?>
            {
                ["name"] = "Ada Lovelace",
                ["email"] = "ada@example.test",
            },
        });

        await Agent.AssertAsync("the welcome screen greets Ada by name");
        await Expect.That(Screen.GetByRole("status")).ToContainTextAsync("trial");
    }
}

Give ActAsync one atomic goal per call. Params fills the placeholders.
AssertAsync asks the model to judge the screen. Expect.That(...) checks an exact value with no model call, so pair each agent step with one.
Tag tests that call a model, for example [Category("RealModel")], so CI can skip them with --filter "TestCategory!=RealModel".

4. Run

dotnet test --project .
E2E_HEADLESS=0 dotnet test --project .      # watch the browser

The first run asks the model to perform each ActAsync. A passing run records each verified step in .e2e/cache, and the next run replays it with no model call.

Dariten sampleA locator test and an agent test against a live public app.

TodoMVC samplePlaywright's TodoMVC suite rewritten as agent steps.

Hosted browsersCDP recovery, hosted browsers, video, and trace in the guide.

Web

1. Create the test project

2. Point at your app

3. Write a test

4. Run

Next