fix: error assertion messages

integration/rust/tests/integration/connection_recovery.rs

@@ -108,11 +108,12 @@ async fn test_client_connection_recovery_default() {
     let result = conn.simple_query("SELECT 1").await;
     assert!(result.is_err(), "Expected error when pools are banned");
     let err = result.unwrap_err();
-    let err_str = err.to_string().to_lowercase();
+    let db_err = err.as_db_error().expect("Expected a DbError");
+    let err_str = db_err.message().to_lowercase();
     assert!(
         err_str.contains("all replicas down"),
         "Expected 'all replicas down' error, got: {}",
-        err
+        err_str
     );
 
     // Unban pools

integration/rust/tests/integration/multi_set.rs

@@ -52,10 +52,11 @@ async fn test_multi_set_mixed_returns_error() {
             .batch_execute("SET statement_timeout TO '10s'; SELECT 1")
             .await
             .unwrap_err();
+        let db_err = err.as_db_error().expect("Expected a DbError");
+        let msg = db_err.message();
         assert!(
-            err.to_string()
-                .contains("multi-statement queries cannot mix SET with other commands"),
-            "unexpected error: {err}",
+            msg.contains("multi-statement queries cannot mix SET with other commands"),
+            "unexpected error: {msg}",
         );
     }
 }