test(core): add quirks and save-state tests

2026-08-28 11:08:22 +02:00
1 parent 219c7b895c
commit dc1d25a0cf
@@ -0,0 +1,104 @@
+using System.IO;
+using Chip8.Core;
+using Xunit;
+
+namespace Chip8.Tests;
+
+public class SaveStateTests
+{
+    [Fact]
+    public void loadStateRestoresRegistersMemoryAndDisplay()
+    {
+        var machine = TestHarness.withProgram(Platform.Chip8, 0x7001, 0x1200);
+        machine.step();
+        machine.v[3] = 0xAB;
+        machine.i = 0x321;
+        machine.memory[0x400] = 0x42;
+        machine.display[5] = true;
+
+        byte[] state = machine.saveState();
+
+        machine.v[3] = 0x00;
+        machine.i = 0x000;
+        machine.memory[0x400] = 0x99;
+        machine.display[5] = false;
+        machine.pc = 0x2FF;
+
+        machine.loadState(state);
+
+        Assert.Equal(0xAB, machine.v[3]);
+        Assert.Equal(0x321, machine.i);
+        Assert.Equal(0x42, machine.memory[0x400]);
+        Assert.True(machine.display[5]);
+        Assert.Equal(0x202, machine.pc);
+    }
+
+    [Fact]
+    public void restoreBuildsANewMachineFromState()
+    {
+        var machine = TestHarness.withProgram(Platform.SuperChip, 0x6009);
+        machine.step();
+        byte[] state = machine.saveState();
+
+        Machine restored = Machine.restore(state);
+
+        Assert.Equal(Platform.SuperChip, restored.platform);
+        Assert.Equal(machine.v[0], restored.v[0]);
+        Assert.Equal(machine.pc, restored.pc);
+    }
+
+    [Fact]
+    public void restoredMachineExecutesIdenticallyToTheOriginal()
+    {
+        var original = TestHarness.withProgram(Platform.Chip8, 0x7001, 0x1200);
+        for (int step = 0; step < 20; step++)
+        {
+            original.step();
+        }
+
+        Machine resumed = Machine.restore(original.saveState());
+        for (int step = 0; step < 15; step++)
+        {
+            original.step();
+            resumed.step();
+        }
+
+        Assert.Equal(original.pc, resumed.pc);
+        Assert.Equal(original.v[0], resumed.v[0]);
+        Assert.Equal(original.i, resumed.i);
+    }
+
+    [Fact]
+    public void xoChipStatePreservesPlanesAndAudio()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0xF201, 0xA400, 0xD001);
+        machine.memory[0x400] = 0x80;
+        machine.audioPattern[3] = 0xC3;
+        for (int step = 0; step < 3; step++)
+        {
+            machine.step();
+        }
+        Assert.Equal(2, machine.video.colorAt(0, 0));
+
+        Machine restored = Machine.restore(machine.saveState());
+
+        Assert.Equal(2, restored.planeMask);
+        Assert.Equal(2, restored.video.colorAt(0, 0));
+        Assert.Equal(0xC3, restored.audioPattern[3]);
+    }
+
+    [Fact]
+    public void loadStateRejectsAMismatchedPlatform()
+    {
+        var chip8 = new Machine(Quirks.modern(), 1);
+        byte[] state = chip8.saveState();
+        var xoChip = new Machine(null, 1, Platform.XoChip);
+        Assert.Throws<InvalidDataException>(() => xoChip.loadState(state));
+    }
+
+    [Fact]
+    public void restoreRejectsGarbage()
+    {
+        Assert.Throws<InvalidDataException>(() => Machine.restore(new byte[] { 1, 2, 3, 4, 5 }));
+    }
+}