data: simplify and validate Japanese imports

tests/skk2ktrans_test.py

@@ -27,7 +27,14 @@ class Skk2KtransTest(unittest.TestCase):
 		result = subprocess.run(
 			[CONVERTER], input=b"\xff\xff\n", capture_output=True, check=False)
 		self.assertNotEqual(result.returncode, 0)
-		self.assertIn(b"invalid EUC-JP", result.stderr)
+		self.assertTrue(result.stderr)
+
+	def test_escaped_candidate_is_rejected(self):
+		source = b"key /escaped\\/slash/\n"
+		result = subprocess.run(
+			[CONVERTER], input=source, capture_output=True, check=False)
+		self.assertNotEqual(result.returncode, 0)
+		self.assertIn(b"escaped candidates are unsupported", result.stderr)
 
 
 if __name__ == "__main__":