# WriteMessages
```rust
use bevy::prelude::*;
use rmv_bevy_testing_tools::prelude::*;
use rstest::rstest;
#[derive(Debug, Default, Message)]
enum MyMessage { #[default] A, B, C }
#[rstest]
fn some_test(#[from(test_app)] mut app: TestApp) {
app.add_event::<MyMessage>();
app.write_message_default::<MyMessage>();
app.write_message(MyMessage::B);
app.write_message_batch([MyMessage::A, MyMessage::C]);
}
```