first public release

bit_xy_test.go

@@ -0,0 +1,19 @@
+package z80
+
+import "testing"
+
+// Highlights blind spot: BIT n,r should update X/Y from the operand (register form).
+// Current implementation only fixes the (HL) form, so this test will fail until fixed.
+func TestBIT_Reg_SetsXYFromOperand(t *testing.T) {
+	cpu, mem, _ := testCPU()
+	// Load: LD B,0x28 (0010_1000: bit3=1 -> X=1, bit5=1 -> Y=1)
+	loadProgram(cpu, mem, 0x0000,
+		0x06, 0x28, // LD B,28h
+		0xCB, 0x40, // BIT 0,B  (arbitrary bit test that does not force Z)
+	)
+	mustStep(t, cpu) // LD
+	mustStep(t, cpu) // BIT 0,B
+	// Expect X/Y to mirror operand (B) on BIT n,r.
+	assertFlag(t, cpu, FLAG_X, true, "BIT n,r should set X from tested register")
+	assertFlag(t, cpu, FLAG_Y, true, "BIT n,r should set Y from tested register")
+}