diff --git a/tests/basic/test_io.py b/tests/basic/test_io.py
index 89e759dca..642e19863 100644
--- a/tests/basic/test_io.py
+++ b/tests/basic/test_io.py
@@ -162,6 +162,20 @@ class TestInputOutput(unittest.TestCase):
         mock_prompt.assert_called_once()
         mock_prompt.reset_mock()
 
+    def test_get_command_completions(self):
+        root = ""
+        rel_fnames = []
+        addable_rel_fnames = []
+        commands = MagicMock()
+        commands.get_commands.return_value = ["model", "chat", "help"]
+        commands.get_completions.return_value = ["gpt-3.5-turbo", "gpt-4"]
+
+        autocompleter = AutoCompleter(root, rel_fnames, addable_rel_fnames, commands, "utf-8")
+        
+        # Test case for "/model gpt"
+        result = autocompleter.get_command_completions("/model gpt", ["/model", "gpt"])
+        self.assertEqual(result, ["gpt-3.5-turbo", "gpt-4"])
+        commands.get_completions.assert_called_once_with("model")
 
 if __name__ == "__main__":
     unittest.main()