diff --git a/solutions/tests/test_capitalize_string.py b/solutions/tests/test_capitalize_string.py
index 74580bf8d..ad9fe888f 100644
--- a/solutions/tests/test_capitalize_string.py
+++ b/solutions/tests/test_capitalize_string.py
@@ -49,3 +49,7 @@ def test_non_string_input(self):
             capitalize_string(123)
         with self.assertRaises(TypeError):
             capitalize_string(["hello", "world"])
+
+
+if __name__ == "__main__":
+    unittest.main()