Add base test for SDL3 main callbacks

Reduces boilerplate code when writing tests.

SDL3-CS.Tests/MainCallbacksTest.cs

@@ -0,0 +1,107 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using NUnit.Framework;
+
+namespace SDL.Tests
+{
+    /// <summary>
+    /// Base class for tests that use SDL3 main callbacks.
+    /// See https://wiki.libsdl.org/SDL3/README/main-functions#how-to-use-main-callbacks-in-sdl3.
+    /// </summary>
+    [TestFixture]
+    [Apartment(ApartmentState.STA)]
+    public abstract unsafe class MainCallbacksTest
+    {
+        [Test]
+        public void TestEnterMainCallbacks()
+        {
+            var objectHandle = new ObjectHandle<MainCallbacksTest>(this, GCHandleType.Normal);
+            SDL3.SDL_EnterAppMainCallbacks(0, (byte**)objectHandle.Handle, &AppInit, &AppIterate, &AppEvent, &AppQuit);
+        }
+
+        protected virtual int Init()
+        {
+            SDL3.SDL_SetLogPriorities(SDL_LogPriority.SDL_LOG_PRIORITY_VERBOSE);
+            SDL3.SDL_SetLogOutputFunction(&LogOutput, IntPtr.Zero);
+            return CONTINUE;
+        }
+
+        protected const int TERMINATE_ERROR = -1;
+        protected const int CONTINUE = 0;
+        protected const int TERMINATE_SUCCESS = 1;
+
+        protected virtual int Iterate()
+        {
+            Thread.Sleep(10);
+            return CONTINUE;
+        }
+
+        protected virtual int Event(SDL_Event e)
+        {
+            switch (e.Type)
+            {
+                case SDL_EventType.SDL_EVENT_QUIT:
+                case SDL_EventType.SDL_EVENT_WINDOW_CLOSE_REQUESTED:
+                case SDL_EventType.SDL_EVENT_TERMINATING:
+                case SDL_EventType.SDL_EVENT_KEY_DOWN when e.key.keysym.sym == SDL_Keycode.SDLK_ESCAPE:
+                    return TERMINATE_SUCCESS;
+            }
+
+            return CONTINUE;
+        }
+
+        protected virtual void Quit()
+        {
+        }
+
+        [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
+        private static void LogOutput(IntPtr userdata, SDL_LogCategory category, SDL_LogPriority priority, byte* message)
+        {
+            Console.WriteLine(SDL3.PtrToStringUTF8(message));
+        }
+
+        [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
+        private static int AppInit(IntPtr* appState, int argc, byte** argv)
+        {
+            IntPtr handle = (IntPtr)argv;
+            *appState = handle;
+
+            var objectHandle = new ObjectHandle<MainCallbacksTest>(handle, true);
+            if (objectHandle.GetTarget(out var target))
+                return target.Init();
+
+            return TERMINATE_ERROR;
+        }
+
+        [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
+        private static int AppIterate(IntPtr appState)
+        {
+            var objectHandle = new ObjectHandle<MainCallbacksTest>(appState, true);
+            if (objectHandle.GetTarget(out var target))
+                return target.Iterate();
+
+            return TERMINATE_ERROR;
+        }
+
+        [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
+        private static int AppEvent(IntPtr appState, SDL_Event* e)
+        {
+            var objectHandle = new ObjectHandle<MainCallbacksTest>(appState, true);
+            if (objectHandle.GetTarget(out var target))
+                return target.Event(*e);
+
+            return TERMINATE_ERROR;
+        }
+
+        [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
+        private static void AppQuit(IntPtr appState)
+        {
+            using var objectHandle = new ObjectHandle<MainCallbacksTest>(appState, true);
+            if (objectHandle.GetTarget(out var target))
+                target.Quit();
+        }
+    }
+}