Add test for xor a asm instruction

Test for both dependency and evaluated values.

Author: boriel

tests/arch/zx48k/backend/test_memcell.py

@@ -122,3 +122,10 @@ def test_require_destroys_asm(self):
                                       'r', 'i', 'sp'})
 
         del arch.zx48k.backend.ASMS['##ASM0']
+
+    def test_requires_xor_a(self):
+        """ Test requires for xor a instruction
+        """
+        c = memcell.MemCell('xor a', 1)
+        self.assertSetEqual(c.requires, set())
+        self.assertSetEqual(c.destroys, {'a', 'f'})

tests/arch/zx48k/optimizer/test_cpustate.py

@@ -296,3 +296,13 @@ def test_reset_mem(self):
         self.cpu_state.mem['_test'] = '5'
         self.cpu_state.reset()
         self.assertNotEqual(self.cpu_state.mem['_test'], '5')
+
+    def test_xor_a(self):
+        code = """
+        xor a
+        """
+        self._eval(code)
+        self.assertEqual(self.regs['a'], '0')
+        self.assertEqual(self.cpu_state.C, 0)
+        self.assertEqual(self.cpu_state.Z, 1)
+        # Must not crash