fix: Fix headless gui and clock keeping references to emulator and making tests very memory hungry. Added a test to verify this doesnt happen anymore.

src/Spice86.MicroBenchmarkTemplate/Spice86.MicroBenchmarkTemplate.csproj

@@ -3,6 +3,7 @@
     <PropertyGroup>
         <IsPackable>False</IsPackable>
         <OutputType>Exe</OutputType>
+        <StartupObject>Spice86.MicroBenchmarkTemplate.Program</StartupObject>
         <TargetFramework>net10.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
         <Nullable>enable</Nullable>

src/Spice86/Spice86DependencyInjection.cs

@@ -216,12 +216,16 @@ internal Spice86DependencyInjection(Configuration configuration, MainWindow? mai
         }
 
         DateTimeOffset clockStartTime = configuration.ClockStartTime ?? DateTimeOffset.UtcNow;
-        _emulatedClock = configuration.InstructionTimeScale != null
+        IEmulatedClock emulatedClock = configuration.InstructionTimeScale != null
             ? new CyclesClock(state, configuration.InstructionTimeScale.Value, configuration.ClockJitterSeed, clockStartTime)
             : new EmulatedClock(configuration.ClockJitterSeed, clockStartTime);
-        // Register clock and limiter to pause/resume events
-        pauseHandler.Pausing += () => _emulatedClock.OnPause();
-        pauseHandler.Resumed += () => _emulatedClock.OnResume();
+        _emulatedClock = emulatedClock;
+        // Register clock and limiter to pause/resume events. Capture the clock through a local rather than the
+        // field so the event delegates do not close over this Spice86DependencyInjection instance: the pause
+        // handler can be rooted independently (e.g. by the MCP host service graph), and a closure over 'this'
+        // would keep the whole Machine graph alive after disposal.
+        pauseHandler.Pausing += () => emulatedClock.OnPause();
+        pauseHandler.Resumed += () => emulatedClock.OnResume();
 
         DeviceScheduler emulationLoopScheduler = new(_emulatedClock, loggerService, "Emulation loop");
         FloppyDiskTimingService floppyDiskTimingService = new(state, _emulatedClock, emulationLoopScheduler, FloppyDiskSpeed.Maximum);

src/Spice86/ViewModels/Services/HeadlessGui.cs

@@ -130,6 +130,12 @@ private void Dispose(bool disposing) {
             return;
         }
 
+        // These are process-lifetime static events; without unsubscribing they keep every
+        // HeadlessGui instance (and the whole Machine graph it references) alive for the
+        // lifetime of the process, which leaks an entire emulator per instance.
+        AppDomain.CurrentDomain.ProcessExit -= OnProcessExit;
+        Console.CancelKeyPress -= OnProcessExit;
+
         // Stop the timer to prevent any new callbacks
         _drawTimer?.Dispose();
 

tests/Spice86.Tests/CpuTests/SingleStepTests/SingleStepTest.cs

@@ -152,7 +152,7 @@ private void RunAllTests(ZipArchive archive, ISet<string> revocationList, ISet<s
                     _testRunner.RunTest(cpuTest, index++, entry.Name, _singleStepTestMinimalMachine, maxCycles, flagsMask);
                 } catch (Exception ex) {
                     testPassed = false;
-                    errorMessage = ex.Message;
+                    errorMessage = ex.ToString();
                     if (!GenerateRevocationList && OpcodeToFix == null) {
                         throw;
                     }

tests/Spice86.Tests/Http/HttpApiGeneratedClientIntegrationTests.cs

@@ -10,8 +10,7 @@ namespace Spice86.Tests.Http;
 
 using Xunit;
 
-[Collection(HttpApiServerCollection.Name)]
-public sealed partial class HttpApiGeneratedClientIntegrationTests {
+public sealed partial class HttpApiGeneratedClientIntegrationTests : IClassFixture<HttpApiServerFixture> {
     private const string KiotaToolVersion = "1.30.0";
     private static readonly TimeSpan CommandTimeout = TimeSpan.FromMinutes(3);
     private readonly HttpApiServerFixture _fixture;
@@ -25,6 +24,10 @@ public HttpApiGeneratedClientIntegrationTests(HttpApiServerFixture fixture) {
     [InlineData("yaml", "/openapi/v1.yaml")]
     public async Task KiotaGeneratedDotNetClient_CanBeGeneratedBuiltAndExecuted(string extension, string openApiPath) {
         // Arrange
+        _fixture.Memory[0x40] = 0x12;
+        _fixture.Memory[0x41] = 0x34;
+        _fixture.Memory[0x42] = 0x56;
+        _fixture.Memory[0x43] = 0x78;
         _fixture.PauseHandler.IsPaused.Returns(false);
         _fixture.PauseHandler.ClearReceivedCalls();
         TestWorkspace workspace = CreateTestWorkspace(extension);

tests/Spice86.Tests/Http/HttpApiServerTests.cs

@@ -30,11 +30,12 @@ private void SeedMemory() {
     [Fact]
     public async Task GetStatus_ReturnsMachineState() {
         SeedMemory();
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/status");
+        _fixture.PauseHandler.IsPaused.Returns(false);
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/status", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
 
-        HttpApiStatusResponse payload = await response.Content.ReadFromJsonAsync<HttpApiStatusResponse>()
+        HttpApiStatusResponse payload = await response.Content.ReadFromJsonAsync<HttpApiStatusResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.IsPaused.Should().BeFalse();
         payload.IsCpuRunning.Should().BeTrue();
@@ -47,11 +48,11 @@ public async Task GetStatus_ReturnsMachineState() {
     [Fact]
     public async Task GetByte_ReturnsByteAtAddress() {
         SeedMemory();
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/byte");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/byte", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
 
-        HttpApiMemoryByteResponse payload = await response.Content.ReadFromJsonAsync<HttpApiMemoryByteResponse>()
+        HttpApiMemoryByteResponse payload = await response.Content.ReadFromJsonAsync<HttpApiMemoryByteResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.Address.Should().Be(64);
         payload.Value.Should().Be(0x12);
@@ -63,7 +64,7 @@ public async Task GetByte_WhenNotPaused_PausesThenUnpauses() {
         _fixture.PauseHandler.ClearReceivedCalls();
         _fixture.PauseHandler.IsPaused.Returns(false);
 
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/byte");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/byte", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
         _fixture.PauseHandler.Received(1).RequestPause(Arg.Any<string>());
@@ -76,7 +77,7 @@ public async Task GetByte_WhenAlreadyPaused_DoesNotUnpause() {
         _fixture.PauseHandler.ClearReceivedCalls();
         _fixture.PauseHandler.IsPaused.Returns(true);
 
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/byte");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/byte", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
         _fixture.PauseHandler.DidNotReceive().RequestPause(Arg.Any<string>());
@@ -90,15 +91,15 @@ public async Task PutByte_WritesAndReadsBackValue() {
             Value = 0xAB
         };
 
-        HttpResponseMessage putResponse = await _fixture.HttpClient.PutAsJsonAsync("/api/memory/64/byte", request);
+        HttpResponseMessage putResponse = await _fixture.HttpClient.PutAsJsonAsync("/api/memory/64/byte", request, TestContext.Current.CancellationToken);
         putResponse.StatusCode.Should().Be(HttpStatusCode.OK);
 
-        HttpApiMemoryByteResponse putPayload = await putResponse.Content.ReadFromJsonAsync<HttpApiMemoryByteResponse>()
+        HttpApiMemoryByteResponse putPayload = await putResponse.Content.ReadFromJsonAsync<HttpApiMemoryByteResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null putPayload");
         putPayload.Value.Should().Be(0xAB);
 
-        HttpResponseMessage getResponse = await _fixture.HttpClient.GetAsync("/api/memory/64/byte");
-        HttpApiMemoryByteResponse getPayload = await getResponse.Content.ReadFromJsonAsync<HttpApiMemoryByteResponse>()
+        HttpResponseMessage getResponse = await _fixture.HttpClient.GetAsync("/api/memory/64/byte", TestContext.Current.CancellationToken);
+        HttpApiMemoryByteResponse getPayload = await getResponse.Content.ReadFromJsonAsync<HttpApiMemoryByteResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null getPayload");
         getPayload.Value.Should().Be(0xAB);
         _fixture.Memory[0x40].Should().Be(0xAB);
@@ -113,7 +114,7 @@ public async Task PutByte_WhenNotPaused_PausesThenUnpauses() {
             Value = 0xCD
         };
 
-        HttpResponseMessage response = await _fixture.HttpClient.PutAsJsonAsync("/api/memory/64/byte", request);
+        HttpResponseMessage response = await _fixture.HttpClient.PutAsJsonAsync("/api/memory/64/byte", request, TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
         _fixture.PauseHandler.Received(1).RequestPause(Arg.Any<string>());
@@ -123,11 +124,11 @@ public async Task PutByte_WhenNotPaused_PausesThenUnpauses() {
     [Fact]
     public async Task GetRange_ReturnsRequestedRange() {
         SeedMemory();
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/range/4");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/range/4", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
 
-        HttpApiMemoryRangeResponse payload = await response.Content.ReadFromJsonAsync<HttpApiMemoryRangeResponse>()
+        HttpApiMemoryRangeResponse payload = await response.Content.ReadFromJsonAsync<HttpApiMemoryRangeResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.Address.Should().Be(64);
         payload.Length.Should().Be(4);
@@ -138,7 +139,7 @@ public async Task GetRange_ReturnsRequestedRange() {
     public async Task PauseEndpoint_PausesEmulator() {
         _fixture.PauseHandler.ClearReceivedCalls();
 
-        HttpResponseMessage response = await _fixture.HttpClient.PostAsync("/api/status/pause", content: null);
+        HttpResponseMessage response = await _fixture.HttpClient.PostAsync("/api/status/pause", content: null, TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
         _fixture.PauseHandler.Received(1).RequestPause(Arg.Any<string>());
@@ -148,7 +149,7 @@ public async Task PauseEndpoint_PausesEmulator() {
     public async Task UnpauseEndpoint_ResumesEmulator() {
         _fixture.PauseHandler.ClearReceivedCalls();
 
-        HttpResponseMessage response = await _fixture.HttpClient.PostAsync("/api/status/unpause", content: null);
+        HttpResponseMessage response = await _fixture.HttpClient.PostAsync("/api/status/unpause", content: null, TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
         _fixture.PauseHandler.Received(1).Resume();
@@ -161,11 +162,11 @@ public async Task GetRange_TruncatesAtMemoryEnd() {
         _fixture.Memory[(uint)lastAddress] = 0x9A;
         _fixture.Memory[(uint)(lastAddress + 1)] = 0xBC;
 
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync($"/api/memory/{lastAddress}/range/16");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync($"/api/memory/{lastAddress}/range/16", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
 
-        HttpApiMemoryRangeResponse payload = await response.Content.ReadFromJsonAsync<HttpApiMemoryRangeResponse>()
+        HttpApiMemoryRangeResponse payload = await response.Content.ReadFromJsonAsync<HttpApiMemoryRangeResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.Length.Should().Be(2);
         payload.Values.Should().Equal([0x9A, 0xBC]);
@@ -174,35 +175,35 @@ public async Task GetRange_TruncatesAtMemoryEnd() {
     [Fact]
     public async Task GetByte_WithNegativeAddress_ReturnsBadRequest() {
         SeedMemory();
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/-1/byte");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/-1/byte", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
 
-        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>()
+        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.Message.Should().Contain("between 0 and 4294967295");
     }
 
     [Fact]
     public async Task GetByte_WithAddressTooLarge_ReturnsBadRequest() {
         SeedMemory();
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/4294967296/byte");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/4294967296/byte", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
 
-        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>()
+        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.Message.Should().Contain("between 0 and 4294967295");
     }
 
     [Fact]
     public async Task GetByte_WithOutOfRangeAddress_ReturnsNotFound() {
         SeedMemory();
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync($"/api/memory/{_fixture.Memory.Length}/byte");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync($"/api/memory/{_fixture.Memory.Length}/byte", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.NotFound);
 
-        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>()
+        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.Message.Should().Be("address is outside of memory range");
     }
@@ -211,23 +212,23 @@ public async Task GetByte_WithOutOfRangeAddress_ReturnsNotFound() {
     public async Task GetRange_WithExcessiveLength_ReturnsBadRequest() {
         SeedMemory();
         int excessiveLength = HttpApiEndpoint.MaxRangeLength + 1;
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync($"/api/memory/64/range/{excessiveLength}");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync($"/api/memory/64/range/{excessiveLength}", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
 
-        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>()
+        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.Message.Should().Contain($"{HttpApiEndpoint.MaxRangeLength}");
     }
 
     [Fact]
     public async Task GetRange_WithInvalidLength_ReturnsBadRequest() {
         SeedMemory();
-        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/range/0");
+        HttpResponseMessage response = await _fixture.HttpClient.GetAsync("/api/memory/64/range/0", TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
 
-        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>()
+        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.Message.Should().Be("length must be greater than 0");
     }
@@ -239,11 +240,11 @@ public async Task PutByte_WithOutOfRangeAddress_ReturnsNotFound() {
             Value = 0xEF
         };
 
-        HttpResponseMessage response = await _fixture.HttpClient.PutAsJsonAsync($"/api/memory/{_fixture.Memory.Length}/byte", request);
+        HttpResponseMessage response = await _fixture.HttpClient.PutAsJsonAsync($"/api/memory/{_fixture.Memory.Length}/byte", request, TestContext.Current.CancellationToken);
 
         response.StatusCode.Should().Be(HttpStatusCode.NotFound);
 
-        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>()
+        HttpApiErrorResponse payload = await response.Content.ReadFromJsonAsync<HttpApiErrorResponse>(TestContext.Current.CancellationToken)
             ?? throw new InvalidOperationException("Expected non-null payload");
         payload.Message.Should().Be("address is outside of memory range");
     }

tests/Spice86.Tests/MachineLeakGuard.cs

@@ -0,0 +1,24 @@
+[assembly: Xunit.AssemblyFixture(typeof(Spice86.Tests.MachineLeakGuard))]
+
+namespace Spice86.Tests;
+
+using Xunit;
+
+/// <summary>
+/// Assembly-wide guard that runs once after every test in the assembly has completed. It fails the run if
+/// any emulator instance created through <see cref="Spice86Creator"/> is still reachable after disposal and
+/// garbage collection, which would indicate a reference leak pinning the whole Machine graph.
+/// </summary>
+public sealed class MachineLeakGuard : IDisposable {
+    public void Dispose() {
+        int tracked = MachineLeakTracker.TrackedCount;
+        if (tracked == 0) {
+            return;
+        }
+
+        int surviving = MachineLeakTracker.CountSurvivingAfterCollection();
+        Assert.True(surviving == 0,
+            $"{surviving} of {tracked} emulator instances created via Spice86Creator were still alive after " +
+            "disposal and garbage collection. This indicates a reference leak that keeps the entire Machine graph rooted.");
+    }
+}

tests/Spice86.Tests/MachineLeakTracker.cs

@@ -0,0 +1,39 @@
+namespace Spice86.Tests;
+
+using Spice86.Core.Emulator.VM;
+
+/// <summary>
+/// Tracks weak references to every <see cref="Machine"/> created through <see cref="Spice86Creator"/>.
+/// A suite-wide check verifies that disposed emulator instances become collectible: a single rooted
+/// Machine keeps its entire device, CFG and memory graph alive, and accumulating those across the suite
+/// previously exhausted host memory.
+/// </summary>
+internal static class MachineLeakTracker {
+    private static readonly List<WeakReference> TrackedMachines = new();
+    private static readonly object SyncRoot = new();
+
+    public static void Track(Machine machine) {
+        lock (SyncRoot) {
+            TrackedMachines.Add(new WeakReference(machine));
+        }
+    }
+
+    public static int TrackedCount {
+        get {
+            lock (SyncRoot) {
+                return TrackedMachines.Count;
+            }
+        }
+    }
+
+    public static int CountSurvivingAfterCollection() {
+        for (int i = 0; i < 3; i++) {
+            GC.Collect();
+            GC.WaitForPendingFinalizers();
+            GC.Collect();
+        }
+        lock (SyncRoot) {
+            return TrackedMachines.Count(reference => reference.IsAlive);
+        }
+    }
+}