Write a simpler test

bindings_ffi/src/mls.rs

@@ -2514,7 +2514,7 @@ mod tests {
         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 2 epochs (as Alix's max_past_epochs is
+        // 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![
@@ -2530,15 +2530,15 @@ mod tests {
             ])
             .await
             .unwrap();
-        // alix_group
-        //     .add_members(vec![
-        //         eri.account_address.clone(),
-        //         frankie.account_address.clone(),
-        //     ])
-        //     .await
-        //     .unwrap();
+        alix_group
+            .add_members(vec![
+                eri.account_address.clone(),
+                frankie.account_address.clone(),
+            ])
+            .await
+            .unwrap();
 
-        // Bo sends messages to Alix while 2 epochs behind
+        // Bo sends messages to Alix while 3 epochs behind
         bo_group.send("bo3".as_bytes().to_vec()).await.unwrap();
         alix_group.send("alix3".as_bytes().to_vec()).await.unwrap();
         bo_group.send("bo4".as_bytes().to_vec()).await.unwrap();
@@ -2553,8 +2553,8 @@ mod tests {
         let bo_messages = bo_group
             .find_messages(FfiListMessagesOptions::default())
             .unwrap();
-        assert_eq!(bo_messages.len(), 8);
-        assert_eq!(alix_messages.len(), 9);
+        assert_eq!(bo_messages.len(), 9);
+        assert_eq!(alix_messages.len(), 10);
 
         assert_eq!(
             bo_messages[bo_messages.len() - 1].id,

xmtp_mls/src/groups/mod.rs

@@ -3364,4 +3364,61 @@ mod tests {
         // group consent state should be allowed if user publishes a message to the group
         assert_eq!(caro_group.consent_state().unwrap(), ConsentState::Allowed);
     }
+
+    // TODO(rich): Generalize the test once fixed - test messages that are 0, 1, 2, 3, 4, 5 epochs behind
+    #[tokio::test]
+    async fn test_max_past_epochs() {
+        // Create group with two members
+        let bo_wallet = generate_local_wallet();
+        let alix = ClientBuilder::new_test_client(&generate_local_wallet()).await;
+        let bo = ClientBuilder::new_test_client(&bo_wallet).await;
+        let alix_group = alix
+            .create_group_with_members(
+                vec![bo_wallet.get_address()],
+                None,
+                GroupMetadataOptions::default(),
+            )
+            .await
+            .unwrap();
+        bo.sync_welcomes().await.unwrap();
+        let bo_groups = bo.find_groups(None, None, None, None).unwrap();
+        let bo_group = bo_groups.first().unwrap();
+
+        // Both members see the same amount of messages to start
+        alix_group
+            .send_message("alix 1".as_bytes(), &alix)
+            .await
+            .unwrap();
+        bo_group.send_message("bo 1".as_bytes(), &bo).await.unwrap();
+        alix_group.sync(&alix).await.unwrap();
+        bo_group.sync(&bo).await.unwrap();
+        let alix_messages = alix_group
+            .find_messages(Some(GroupMessageKind::Application), None, None, None, None)
+            .unwrap();
+        let bo_messages = bo_group
+            .find_messages(Some(GroupMessageKind::Application), None, None, None, None)
+            .unwrap();
+        assert_eq!(alix_messages.len(), 2);
+        assert_eq!(bo_messages.len(), 2);
+
+        // Alix moves the group forward by 1 epoch
+        alix_group
+            .update_group_name(&alix, "new name".to_string())
+            .await
+            .unwrap();
+        // Bo sends a message while 1 epoch behind
+        bo_group.send_message("bo 2".as_bytes(), &bo).await.unwrap();
+
+        // If max_past_epochs is working, Alix should be able to decrypt Bo's message
+        alix_group.sync(&alix).await.unwrap();
+        bo_group.sync(&bo).await.unwrap();
+        let alix_messages = alix_group
+            .find_messages(Some(GroupMessageKind::Application), None, None, None, None)
+            .unwrap();
+        let bo_messages = bo_group
+            .find_messages(Some(GroupMessageKind::Application), None, None, None, None)
+            .unwrap();
+        assert_eq!(bo_messages.len(), 3);
+        assert_eq!(alix_messages.len(), 3); // Fails here, 2 != 3
+    }
 }