decePubClient/tests/e2e/Support/Browser.cs

using Microsoft.Playwright;

[assembly: AssemblyFixture(typeof(decePubClient.E2E.Support.Browser))]

namespace decePubClient.E2E.Support
{
	// One Chromium for the whole run. *.test names go to Caddy on 127.0.0.1:6443 (Chromium's own --resolve), whose
	// certificates come from the pasture's private CA, so certificate errors are ignored; nothing else is reachable.
	public sealed class Browser : IAsyncLifetime
	{
		IPlaywright _playwright;
		public IBrowser Chromium { get; private set; }

		public async ValueTask InitializeAsync()
		{
			_playwright = await Playwright.CreateAsync();
			Chromium = await _playwright.Chromium.LaunchAsync(new()
			{
				Headless = Environment.GetEnvironmentVariable("E2E_HEADED") != "1",
				Args = ["--host-resolver-rules=MAP *.test 127.0.0.1:6443"]
			});
		}

		public async ValueTask DisposeAsync()
		{
			if (Chromium is not null)
				await Chromium.CloseAsync();
			_playwright?.Dispose();
		}

		// a desktop window of 1440x900, or a phone: touch, a coarse pointer, its size and scale, reduced motion so nothing is
		// measured halfway through a transition, and the mobile tests' measuring script (Mobile/fit.js) on every page
		public async Task<Session> Open(string storageState = null, Phone phone = null)
		{
			var options = phone is null
				? new BrowserNewContextOptions { ViewportSize = new() { Width = 1440, Height = 900 } }
				: new BrowserNewContextOptions(_playwright.Devices[phone.Preset]) { ReducedMotion = ReducedMotion.Reduce };
			if (phone is { Width: > 0 })
			{
				options.ViewportSize = new() { Width = phone.Width, Height = phone.Height };
				options.ScreenSize = new() { Width = phone.Width, Height = phone.Height };
			}
			options.IgnoreHTTPSErrors = true;
			options.Locale = "en-GB";
			options.TimezoneId = "Europe/Rome";
			options.ServiceWorkers = ServiceWorkerPolicy.Block;
			options.StorageStatePath = storageState;
			var context = await Chromium.NewContextAsync(options);
			if (phone is not null)
				await context.AddInitScriptAsync(Mobile.Fit.Script);
			return new Session(context, await context.NewPageAsync(), phone);
		}
	}

	// A phone the tests hold: one of Playwright's device presets (they ship inside its package, nothing is downloaded),
	// at its own size or at another one
	public sealed record Phone(string Key, string Preset, int Width = 0, int Height = 0)
	{
		public static readonly Phone Narrow360 = new("narrow360", "Pixel 7", 360, 800);
		public static readonly Phone IPhoneSE3 = new("iphone-se3", "iPhone SE (3rd gen)");
		public static readonly Phone Pixel7 = new("pixel7", "Pixel 7");
		public static readonly Phone Pixel7Landscape = new("pixel7-landscape", "Pixel 7 landscape");

		public static readonly Phone[] Portrait = [Narrow360, IPhoneSE3, Pixel7];

		public static Phone ByKey(string key) => new[] { Narrow360, IPhoneSE3, Pixel7, Pixel7Landscape }.Single(p => p.Key == key);
	}

	// A browser tab and what it did: every request's host, every console error, every 5xx and Blazor's error bar. The
	// guards hold for every test: the app talks only to its own site and to PrivaPub, and never fails silently.
	public sealed class Session : IAsyncDisposable
	{
		public IBrowserContext Context { get; }
		public IPage Page { get; }
		public List<string> Hosts { get; } = [];
		public List<string> ConsoleErrors { get; } = [];
		public List<string> ServerErrors { get; } = [];
		public List<(string Url, string Authorization)> ApiCalls { get; } = [];

		public Phone Phone { get; }

		public Session(IBrowserContext context, IPage page, Phone phone = null)
		{
			Context = context;
			Page = page;
			Phone = phone;
			page.Request += (_, request) =>
			{
				var uri = new Uri(request.Url);
				if (uri.Scheme is "http" or "https")
					lock (Hosts)
						Hosts.Add(uri.Host);
				if (uri.Host == "privapub.test")
					lock (ApiCalls)
						ApiCalls.Add((request.Url, request.Headers.TryGetValue("authorization", out var auth) ? auth : null));
			};
			page.Console += (_, message) =>
			{
				if (message.Type == "error")
					lock (ConsoleErrors)
						ConsoleErrors.Add(message.Text);
			};
			page.Response += (_, response) =>
			{
				if (response.Status >= 500)
					lock (ServerErrors)
						ServerErrors.Add($"{response.Status} {response.Url}");
			};
		}

		public async Task AssertGuards()
		{
			Assert.All(Hosts.Distinct(), host => Assert.Contains(host, new[] { "decepub.test", "privapub.test" }));
			Assert.Empty(ServerErrors);
			Assert.False(await Page.Locator("#blazor-error-ui").IsVisibleAsync(), "Blazor's error bar is showing");
			// /clientapi carries the root's JWT and /api a persona's token: no credential ever crosses over
			var clientApi = ApiCalls.Where(c => c.Authorization is not null && new Uri(c.Url).AbsolutePath.StartsWith("/clientapi/"))
				.Select(c => c.Authorization).ToHashSet();
			var mastodonApi = ApiCalls.Where(c => c.Authorization is not null && new Uri(c.Url).AbsolutePath.StartsWith("/api/"))
				.Select(c => c.Authorization).ToHashSet();
			Assert.Empty(clientApi.Intersect(mastodonApi));
			Assert.All(clientApi, auth => Assert.Equal(3, auth["Bearer ".Length..].Split('.').Length));
		}

		// a phone session that answers like a desktop would test desktop sizes without saying so: the page must see touch
		public async Task AssertPhone()
		{
			if (Phone is null)
				return;
			Assert.True(await Page.EvaluateAsync<bool>("() => matchMedia('(pointer: coarse)').matches && matchMedia('(hover: none)').matches"),
				$"{Phone.Key} is not emulated as a touch screen");
		}

		public async ValueTask DisposeAsync() => await Context.CloseAsync();
	}
}