diff --git a/bin/key-mapper-service b/bin/key-mapper-service
index ab5b21cc..444f1962 100755
--- a/bin/key-mapper-service
+++ b/bin/key-mapper-service
@@ -86,7 +86,6 @@ if __name__ == '__main__':
     log_info()
 
     if options.key_names:
-        # TODO test
         print('\n'.join(system_mapping.list_names()))
         sys.exit(0)
 
diff --git a/keymapper/dev/permissions.py b/keymapper/dev/permissions.py
index b7b4c014..04dc28df 100644
--- a/keymapper/dev/permissions.py
+++ b/keymapper/dev/permissions.py
@@ -34,7 +34,6 @@ from keymapper.paths import USER
 
 def check_group(group):
     """Check if the required group is active and log if not."""
-    # TODO test
     try:
         in_group = USER in grp.getgrnam(group).gr_mem
     except KeyError:
diff --git a/keymapper/state.py b/keymapper/state.py
index dd3b083a..9b5a822e 100644
--- a/keymapper/state.py
+++ b/keymapper/state.py
@@ -43,7 +43,6 @@ class SystemMapping:
 
     def list_names(self):
         """Return an array of all possible names in the mapping."""
-        # TODO test
         return self._mapping.keys()
 
     def populate(self):
@@ -70,7 +69,7 @@ class SystemMapping:
                     self._set(name, int(keycode) - XKB_KEYCODE_OFFSET)
 
         for name, ecode in evdev.ecodes.ecodes.items():
-            if name.startswith('KEY') or name.startswith('KEY'):
+            if name.startswith('KEY') or name.startswith('BTN'):
                 self._set(name, ecode)
 
     def _set(self, name, code):
diff --git a/tests/testcases/test_keycode_mapper.py b/tests/testcases/test_keycode_mapper.py
index 1c994533..7dbbecda 100644
--- a/tests/testcases/test_keycode_mapper.py
+++ b/tests/testcases/test_keycode_mapper.py
@@ -35,5 +35,7 @@ class TestKeycodeMapper(unittest.TestCase):
 
     # TODO test for macro holding
 
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/testcases/test_mapping.py b/tests/testcases/test_mapping.py
index 7f22d65a..70b070d6 100644
--- a/tests/testcases/test_mapping.py
+++ b/tests/testcases/test_mapping.py
@@ -43,6 +43,8 @@ class TestMapping(unittest.TestCase):
         self.assertEqual(system_mapping.get('kEY_LeFTSHIFT'), 42)
         self.assertEqual(system_mapping.get('ShiFt_L'), 42)
 
+        self.assertEqual(system_mapping.get('BTN_left'), 272)
+
         self.assertIsNotNone(system_mapping.get('kp_1'))
         self.assertIsNotNone(system_mapping.get('KP_1'))
         self.assertEqual(
@@ -54,6 +56,19 @@ class TestMapping(unittest.TestCase):
             system_mapping.get('KEY_KP4')
         )
 
+        names = system_mapping.list_names()
+        self.assertIn('key_kp1', names)
+        self.assertIn('key_nextsong', names)
+        self.assertIn('2', names)
+        self.assertIn('key_3', names)
+        self.assertIn('c', names)
+        self.assertIn('key_d', names)
+        self.assertIn('f4', names)
+        self.assertIn('key_f5', names)
+        self.assertIn('minus', names)
+        self.assertIn('btn_left', names)
+        self.assertIn('btn_right', names)
+
     def test_clone(self):
         mapping1 = Mapping()
         mapping1.change((EV_KEY, 1), 'a')