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Updating to .NET 8, updating to IHostBuilder, and operating Playwright Exams inside NUnit headless or headed on any OS

All the Unit Tests passI have been doing not simply Unit Testing for my websites however full on Integration Testing and Browser Automation Testing as early as 2007 with Selenium. Recently, nevertheless, I have been utilizing the sooner and usually extra appropriate Playwright. It has one API and might check on Home windows, Linux, Mac, domestically, in a container (headless), in my CI/CD pipeline, on Azure DevOps, or in GitHub Actions.

For me, it is that final second of reality to make it possible for the location runs fully from finish to finish.

I can write these Playwright exams in one thing like TypeScript, and I may launch them with node, however I like operating finish unit exams and utilizing that check runner and check harness as my leaping off level for my .NET purposes. I am used to proper clicking and “run unit exams” and even higher, proper click on and “debug unit exams” in Visible Studio or VS Code. This will get me the good thing about the entire assertions of a full unit testing framework, and all the advantages of utilizing one thing like Playwright to automate my browser.

In 2018 I used to be utilizing WebApplicationFactory and a few difficult hacks to mainly spin up ASP.NET inside .NET (on the time) Core 2.1 inside the unit exams after which launching Selenium. This was sort of janky and would require to manually begin a separate course of and handle its life cycle. Nonetheless, I stored on with this hack for a lot of years mainly attempting to get the Kestrel Net Server to spin up within my unit exams.

I’ve lately upgraded my fundamental website and podcast website to .NET 8. Remember that I have been transferring my web sites ahead from early early variations of .NET to the latest variations. The weblog is fortunately operating on Linux in a container on .NET 8, however its authentic code began in 2002 on .NET 1.1.

Now that I am on .NET 8, I scandalously found (as my unit exams stopped working) that the remainder of the world had moved from IWebHostBuilder to IHostBuilder 5 model of .NET in the past. Gulp. Say what you’ll, however the backward compatibility is spectacular.

As such my code for Program.cs modified from this

public static void Major(string[] args)

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>

to this:

public static void Major(string[] args)

public static IHostBuilder CreateHostBuilder(string[] args) =>
ConfigureWebHostDefaults(WebHostBuilder => WebHostBuilder.UseStartup<Startup>());

Not a serious change on the surface however tidies issues up on the within and units me up with a extra versatile generic host for my internet app.

My unit exams stopped working as a result of my Kestral Net Server hack was now not firing up my server.

Right here is an instance of my purpose from a Playwright perspective inside a .NET NUnit check.

public async Job DoesSearchWork()
await Web page.GotoAsync(Url);

await Web page.Locator("#topbar").GetByRole(AriaRole.Hyperlink, new() { Identify = "episodes" }).ClickAsync();

await Web page.GetByPlaceholder("search and filter").ClickAsync();

await Web page.GetByPlaceholder("search and filter").TypeAsync("spouse");

const string visibleCards = ".showCard:seen";

var ready = await Web page.WaitForSelectorAsync(visibleCards, new PageWaitForSelectorOptions() { Timeout = 500 });

await Count on(Web page.Locator(visibleCards).First).ToBeVisibleAsync();

await Count on(Web page.Locator(visibleCards)).ToHaveCountAsync(5);

I really like this. Good and clear. Actually right here we’re assuming that we’ve got a URL in that first line, which will likely be localhost one thing, after which we assume that our internet software has began up by itself.

Right here is the setup code that begins my new “internet software check builder manufacturing unit,” yeah, the identify is silly however it’s descriptive. Notice the OneTimeSetUp and the OneTimeTearDown. This begins my internet app inside the context of my TestHost. Notice the :0 makes the app discover a port which I then, sadly, need to dig out and put into the Url non-public to be used inside my Unit Exams. Notice that the <Startup> is the truth is my Startup class inside Startup.cs which hosts my app’s pipeline and Configure and ConfigureServices get setup right here so routing all works.

non-public string Url;
non-public WebApplication? _app = null;

public void Setup()
var builder = WebApplicationTestBuilderFactory.CreateBuilder<Startup>();

var startup = new Startup(builder.Atmosphere);
builder.WebHost.ConfigureKestrel(o => o.Hear(IPAddress.Loopback, 0));
_app = builder.Construct();

// pay attention on any native port (therefore the 0)
startup.Configure(_app, _app.Configuration);

//you're kidding me
Url = _app.Providers.GetRequiredService<IServer>().Options.GetRequiredFeature<IServerAddressesFeature>().Addresses.Final();

public async Job TearDown()
await _app.DisposeAsync();

So what horrors are buried in WebApplicationTestBuilderFactory? The primary bit is dangerous and we should always repair it for .NET 9. The remainder is definitely each good, with a hat tip to David Fowler for his assist and steering! That is the magic and the ick in a single small helper class.

public class WebApplicationTestBuilderFactory 
public static WebApplicationBuilder CreateBuilder<T>() the place T : class
//This ungodly code requires an unused reference to the MvcTesting bundle that hooks up
// MSBuild to create the manifest file that's learn right here.
var testLocation = Path.Mix(AppContext.BaseDirectory, "MvcTestingAppManifest.json");
var json = JsonObject.Parse(File.ReadAllText(testLocation));
var asmFullName = typeof(T).Meeting.FullName ?? throw new InvalidOperationException("Meeting Full Identify is null");
var contentRootPath = json?[asmFullName]?.GetValue<string>();

//spin up an actual reside internet software inside TestHost.exe
var builder = WebApplication.CreateBuilder(
new WebApplicationOptions()
ContentRootPath = contentRootPath,
ApplicationName = asmFullName
return builder;

The primary 4 strains are nasty. As a result of the check runs within the context of a distinct listing and my web site must run inside the context of its personal content material root path, I’ve to pressure the content material root path to be appropriate and the one manner to try this is by getting the apps base listing from a file generated inside MSBuild from the (growing old) MvcTesting bundle. The bundle is just not used, however by referencing it it will get into the construct and makes that file that I then use to drag out the listing.

If we will eliminate that “hack” and pull the listing from context elsewhere, then this helper operate turns right into a single line and .NET 9 will get WAY WAY extra testable!

Now I can run my Unit Exams AND Playwright Browser Integration Exams throughout all OS’s, headed or headless, in docker or on the metallic. The positioning is up to date to .NET 8 and all is true with my code. Nicely, it runs a minimum of. 😉

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, guide, father, diabetic, and Microsoft worker. He’s a failed stand-up comedian, a cornrower, and a e-book creator.

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