diff --git a/test/test_utils.cpp b/test/test_utils.cpp
index 54e2957..309eaeb 100644
--- a/test/test_utils.cpp
+++ b/test/test_utils.cpp
@@ -151,3 +151,18 @@
     iReplaceAll(str, "abc", "");
     EXPECT_EQ(str, "  ");
 }
+
+TEST(ToLowerCopyTest, BasicTests)
+{
+    EXPECT_EQ(toLowerCopy("HelloWorld"), "helloworld");
+
+    EXPECT_EQ(toLowerCopy("HELLOWORLD"), "helloworld");
+
+    EXPECT_EQ(toLowerCopy("helloworld"), "helloworld");
+
+    EXPECT_EQ(toLowerCopy("123ABC!@#"), "123abc!@#");
+
+    EXPECT_EQ(toLowerCopy("!@#$%^&*()_+"), "!@#$%^&*()_+");
+
+    EXPECT_EQ(toLowerCopy(""), "");
+}