Fix user example tests

Author: Bennett Hardwick

examples/common/user.rs

@@ -30,6 +30,7 @@ impl User {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::borrow::Cow;
     use cipherstash_dynamodb::{IndexType, SingleIndex};
 
     #[test]
@@ -57,12 +58,12 @@ mod tests {
         assert_eq!(
             User::protected_indexes(),
             vec![
-                ("email", IndexType::Single(SingleIndex::Exact)),
+                (Cow::Borrowed("email"), IndexType::Single(SingleIndex::Exact)),
                 (
-                    "email#name",
+                    Cow::Borrowed("email#name"),
                     IndexType::Compound2((SingleIndex::Exact, SingleIndex::Prefix))
                 ),
-                ("name", IndexType::Single(SingleIndex::Prefix)),
+                (Cow::Borrowed("name"), IndexType::Single(SingleIndex::Prefix)),
             ]
         );
     }