Add test to make sure commits work when out of sync

bindings_ffi/src/mls.rs

@@ -2156,6 +2156,66 @@ mod tests {
         assert!(stream_messages.is_closed());
     }
 
+    #[tokio::test(flavor = "multi_thread", worker_threads = 5)]
+    async fn test_can_add_members_when_out_of_sync() {
+        let alix = new_test_client().await;
+        let bo = new_test_client().await;
+        let caro = new_test_client().await;
+        let davon = new_test_client().await;
+        let eri = new_test_client().await;
+        let frankie = new_test_client().await;
+
+        let alix_group = alix
+            .conversations()
+            .create_group(
+                vec![bo.account_address.clone()],
+                FfiCreateGroupOptions::default(),
+            )
+            .await
+            .unwrap();
+
+        bo.conversations().sync().await.unwrap();
+        let bo_group = bo.group(alix_group.id()).unwrap();
+
+        bo_group.send("bo1".as_bytes().to_vec()).await.unwrap();
+        alix_group.send("alix1".as_bytes().to_vec()).await.unwrap();
+
+        // Move the group forward by 3 epochs (as Alix's max_past_epochs is
+        // configured to 3) without Bo syncing
+        alix_group
+            .add_members(vec![
+                caro.account_address.clone(),
+                davon.account_address.clone(),
+            ])
+            .await
+            .unwrap();
+        alix_group
+            .remove_members(vec![
+                caro.account_address.clone(),
+                davon.account_address.clone(),
+            ])
+            .await
+            .unwrap();
+        alix_group
+            .add_members(vec![eri.account_address.clone()])
+            .await
+            .unwrap();
+
+        // Bo adds a member while 3 epochs behind
+        bo_group
+            .add_members(vec![frankie.account_address.clone()])
+            .await
+            .unwrap();
+
+        bo_group.sync().await.unwrap();
+        let bo_members = bo_group.list_members().unwrap();
+        assert_eq!(bo_members.len(), 4);
+
+        alix_group.sync().await.unwrap();
+        let alix_members = alix_group.list_members().unwrap();
+        assert_eq!(alix_members.len(), 4);
+    }
+
     #[tokio::test(flavor = "multi_thread", worker_threads = 5)]
     async fn test_can_send_message_when_out_of_sync() {
         let alix = new_test_client().await;