diff --git a/tests/test_unii_command_data.py b/tests/test_unii_command_data.py
new file mode 100644
index 0000000..b5757ee
--- /dev/null
+++ b/tests/test_unii_command_data.py
@@ -0,0 +1,25 @@
+# pylint: disable=R0801
+# pylint: disable=missing-function-docstring
+"""
+Test UNii Command Data helper functions.
+"""
+
+import logging
+import unittest
+
+from unii.unii_command_data import UNiiBypassMode, UNiiBypassUnbypassZoneInput
+
+_LOGGER = logging.getLogger(__name__)
+
+
+class Test(unittest.TestCase):
+    """
+    Test UNii Command Data helper function correctness.
+    """
+
+    def test_bypass_input(self):
+        data = UNiiBypassUnbypassZoneInput(UNiiBypassMode.USER_CODE, "123456", 1)
+        self.assertEqual(data.mode, 0)
+        self.assertEqual(data.code, "12345600")
+        self.assertEqual(data.number, 1)
+        self.assertEqual(data.to_bytes(), bytes.fromhex("0012345600000000000001"))