diff --git a/tests/test_shell.py b/tests/test_shell.py
index d29b9d3..22bb883 100644
--- a/tests/test_shell.py
+++ b/tests/test_shell.py
@@ -14,5 +14,6 @@ def test_concat_newline():
         [
             concat_newline("hello", "world") == "hello\nworld",
             concat_newline("goodbye", "") == "goodbye",
+            concat_newline() == "",
         ]
     )