test(core): add debugger and watchpoint tests

tests/Chip8.Tests/DebuggerTests.cs

@@ -0,0 +1,115 @@
+using Chip8.Core;
+using Xunit;
+
+namespace Chip8.Tests;
+
+public class DebuggerTests
+{
+    [Fact]
+    public void stepAdvancesProgramCounter()
+    {
+        var machine = TestHarness.withProgram(Platform.Chip8, 0x6001);
+        var debugger = new Debugger(machine);
+        debugger.step();
+        Assert.Equal(0x202, machine.pc);
+        Assert.Equal(1, machine.v[0]);
+    }
+
+    [Fact]
+    public void peekAndDisassembleShowUpcomingInstruction()
+    {
+        var machine = TestHarness.withProgram(Platform.Chip8, 0xA300);
+        var debugger = new Debugger(machine);
+        Assert.Equal(0xA300, debugger.peekOpcode());
+        Assert.Equal("LD I, 0x300", debugger.disassembleNext());
+    }
+
+    [Fact]
+    public void breakpointStopsRunBeforeExecuting()
+    {
+        var machine = TestHarness.withProgram(Platform.Chip8, 0x6001, 0x6102, 0x6203, 0x1200);
+        var debugger = new Debugger(machine);
+        debugger.addBreakpoint(0x204);
+
+        var outcome = debugger.run(100);
+
+        Assert.Equal(StopReason.Breakpoint, outcome.reason);
+        Assert.Equal(2, outcome.steps);
+        Assert.Equal(0x204, machine.pc);
+        Assert.Equal(1, machine.v[0]);
+        Assert.Equal(2, machine.v[1]);
+        Assert.Equal(0, machine.v[2]);
+    }
+
+    [Fact]
+    public void runWithoutBreakpointReachesStepLimit()
+    {
+        var machine = TestHarness.withProgram(Platform.Chip8, 0x1200);
+        var debugger = new Debugger(machine);
+        var outcome = debugger.run(50);
+        Assert.Equal(StopReason.StepLimit, outcome.reason);
+        Assert.Equal(50, outcome.steps);
+    }
+
+    [Fact]
+    public void runStopsWhenInterpreterExits()
+    {
+        var machine = TestHarness.withProgram(Platform.SuperChip, 0x6001, 0x00FD);
+        var debugger = new Debugger(machine);
+        var outcome = debugger.run(100);
+        Assert.Equal(StopReason.Exited, outcome.reason);
+        Assert.True(machine.exited);
+    }
+
+    [Fact]
+    public void snapshotCapturesRegistersStackAndTimers()
+    {
+        var machine = TestHarness.withProgram(Platform.Chip8, 0x2204);
+        var debugger = new Debugger(machine);
+        machine.v[5] = 0x9A;
+        machine.delayTimer = 7;
+
+        debugger.step();
+        var snapshot = debugger.snapshot();
+
+        Assert.Equal(0x204, snapshot.pc);
+        Assert.Equal(1, snapshot.sp);
+        Assert.Single(snapshot.stack);
+        Assert.Equal(0x202, snapshot.stack[0]);
+        Assert.Equal(0x9A, snapshot.v[5]);
+        Assert.Equal(7, snapshot.delayTimer);
+        Assert.Contains("PC=0x0204", snapshot.format());
+        Assert.Contains("V5=9A", snapshot.format());
+    }
+
+    [Fact]
+    public void snapshotIsNotAliasedToLiveState()
+    {
+        var machine = TestHarness.withProgram(Platform.Chip8, 0x6001);
+        var debugger = new Debugger(machine);
+        var snapshot = debugger.snapshot();
+        machine.v[0] = 0xFF;
+        Assert.Equal(0, snapshot.v[0]);
+    }
+
+    [Fact]
+    public void readMemoryReturnsRequestedWindow()
+    {
+        var machine = TestHarness.withProgram(Platform.Chip8, 0xABCD);
+        var debugger = new Debugger(machine);
+        var window = debugger.readMemory(0x200, 2);
+        Assert.Equal(0xAB, window[0]);
+        Assert.Equal(0xCD, window[1]);
+    }
+
+    [Fact]
+    public void breakpointCanBeRemoved()
+    {
+        var machine = TestHarness.withProgram(Platform.Chip8, 0x1200);
+        var debugger = new Debugger(machine);
+        debugger.addBreakpoint(0x200);
+        Assert.True(debugger.hasBreakpoint(0x200));
+        debugger.removeBreakpoint(0x200);
+        Assert.False(debugger.hasBreakpoint(0x200));
+    }
+}