added tests to project

CursorLang.Tests/EndToEndTests.cs

@@ -0,0 +1,153 @@
+using System.Diagnostics;
+using System.IO;
+using System.Reflection;
+
+namespace CursorLang.Tests;
+
+/// <summary>
+/// The application as a whole: the start, the single instance and the exit.
+/// </summary>
+/// <remarks>
+/// The application cannot be built inside the tests — it raises windows and
+/// takes the place of the single instance for the whole session. It is
+/// therefore started the way the user starts it: as a separate process.
+///
+/// If the application is already running in this session, the checks skip
+/// themselves: meddling with someone else's running instance is not their business.
+/// </remarks>
+public sealed class EndToEndTests
+{
+    private static readonly TimeSpan StartTimeout = TimeSpan.FromSeconds(30);
+    private static readonly TimeSpan ExitTimeout = TimeSpan.FromSeconds(15);
+
+    [Fact]
+    public void The_application_starts_and_shows_the_settings_window()
+    {
+        using Launch launch = Launch.Start();
+
+        Assert.NotEqual(IntPtr.Zero, launch.WaitForWindow());
+        Assert.False(launch.Process.HasExited);
+    }
+
+    // A second run raises no second window but shows the window of the running one
+    [Fact]
+    public void The_second_run_ends_by_itself()
+    {
+        using Launch launch = Launch.Start();
+        launch.WaitForWindow();
+
+        using Process second = Launch.StartProcess();
+
+        Assert.True(second.WaitForExit(ExitTimeout), "the second run did not end by itself");
+        Assert.Equal(0, second.ExitCode);
+
+        // And the first one keeps running
+        Assert.False(launch.Process.HasExited);
+    }
+
+    [Fact]
+    public void Closing_the_window_ends_the_application()
+    {
+        using Launch launch = Launch.Start();
+        launch.WaitForWindow();
+
+        Assert.True(launch.Process.CloseMainWindow(), "the window did not accept the request to close");
+        Assert.True(launch.Process.WaitForExit(ExitTimeout), "the application did not end after the window closed");
+        Assert.Equal(0, launch.Process.ExitCode);
+    }
+
+    /// <summary>A started application that shuts down together with the check.</summary>
+    private sealed class Launch : IDisposable
+    {
+        private Launch(Process process) => Process = process;
+
+        internal Process Process { get; }
+
+        /// <summary>Starts the application first — making sure the place is free.</summary>
+        internal static Launch Start()
+        {
+            if (Process.GetProcessesByName("CursorLang").Length > 0)
+            {
+                Assert.Skip("The application is already running — this check keeps out of someone else's run");
+            }
+
+            return new Launch(StartProcess());
+        }
+
+        /// <summary>Starts the application the way the user does.</summary>
+        internal static Process StartProcess()
+        {
+            string path = ExecutablePath();
+
+            if (!File.Exists(path))
+            {
+                Assert.Skip($"The application is not built: {path}");
+            }
+
+            return Process.Start(new ProcessStartInfo(path) { UseShellExecute = true })!;
+        }
+
+        /// <summary>
+        /// Waits for the settings window: by the time it appears the application
+        /// has raised its whole cast.
+        /// </summary>
+        internal IntPtr WaitForWindow()
+        {
+            DateTime deadline = DateTime.UtcNow + StartTimeout;
+
+            while (DateTime.UtcNow < deadline)
+            {
+                Process.Refresh();
+
+                if (Process.HasExited)
+                {
+                    Assert.Fail($"The application exited while starting with code {Process.ExitCode}");
+                }
+
+                if (Process.MainWindowHandle != IntPtr.Zero)
+                {
+                    return Process.MainWindowHandle;
+                }
+
+                Thread.Sleep(100);
+            }
+
+            Assert.Fail("The settings window never appeared");
+            return IntPtr.Zero;
+        }
+
+        private static string ExecutablePath()
+        {
+            string configured = Assembly.GetExecutingAssembly()
+                .GetCustomAttributes<AssemblyMetadataAttribute>()
+                .Single(attribute => attribute.Key == "CursorLangExecutable")
+                .Value!;
+
+            return Path.GetFullPath(configured);
+        }
+
+        public void Dispose()
+        {
+            try
+            {
+                if (!Process.HasExited)
+                {
+                    // The polite way first — that way the app gets to save its settings
+                    if (!Process.CloseMainWindow() || !Process.WaitForExit(ExitTimeout))
+                    {
+                        Process.Kill(entireProcessTree: true);
+                        Process.WaitForExit(ExitTimeout);
+                    }
+                }
+            }
+            catch (InvalidOperationException)
+            {
+                // The process has already ended on its own
+            }
+            finally
+            {
+                Process.Dispose();
+            }
+        }
+    }
+}