diff --git a/tests/test.nim b/tests/test.nim
index f91b2be..1cd744e 100644
--- a/tests/test.nim
+++ b/tests/test.nim
@@ -17,3 +17,11 @@ test "fromSnakeCase":
   check "FIRST_NAME_ONLY".fromSnakeCase() == "firstNameOnly"
   check "ROSTR_TOKEN".fromSnakeCase() == "rostrToken"
 
+test "all lowercase":
+  check "thisisatest".toSnakeCase() == "THISISATEST"
+  check "thisisatest".fromSnakeCase() == "thisisatest"
+
+test "all uppercase":
+  check "THISISATEST".toSnakeCase() == "THISISATEST"
+  check "THISISATEST".fromSnakeCase() == "thisisatest"
+