diff --git a/src/plugins/str.rs b/src/plugins/str.rs
index 430dce76e4..cfa2c608ca 100644
--- a/src/plugins/str.rs
+++ b/src/plugins/str.rs
@@ -297,6 +297,20 @@ mod tests {
         assert!(strutils.filter(subject).is_err());
     }
 
+    #[test]
+    fn str_downcases() {
+        let mut strutils = Str::new();
+        strutils.for_downcase();
+        assert_eq!("andres", strutils.apply("ANDRES"));
+    }
+
+    #[test]
+    fn str_upcases() {
+        let mut strutils = Str::new();
+        strutils.for_upcase();
+        assert_eq!("ANDRES", strutils.apply("andres"));
+    }
+
     #[test]
     fn str_applies_upcase() {
         let mut strutils = Str::new();