use bevy::{ecs::event::Events, prelude::*}; #[derive(Component, Default)] struct Enemy { hit_points: u32, score_value: u32, } struct EnemyDied(u32); #[derive(Resource)] struct Score(u32); fn update_score(mut dead_enemies: EventReader, mut score: ResMut) { for value in dead_enemies.iter() { score.0 += value.0; } } fn despawn_dead_enemies( mut commands: Commands, mut dead_enemies: EventWriter, enemies: Query<(Entity, &Enemy)>, ) { for (entity, enemy) in &enemies { if enemy.hit_points == 0 { commands.entity(entity).despawn_recursive(); dead_enemies.send(EnemyDied(enemy.score_value)); } } } fn hurt_enemies(mut enemies: Query<&mut Enemy>) { for mut enemy in &mut enemies { enemy.hit_points -= 1; } } fn spawn_enemy(mut commands: Commands, keyboard_input: Res>) { if keyboard_input.just_pressed(KeyCode::Space) { commands.spawn(Enemy { hit_points: 5, score_value: 3, }); } } #[test] fn did_hurt_enemy() { // Setup app let mut app = App::new(); // Add Score resource app.insert_resource(Score(0)); // Add `EnemyDied` event app.add_event::(); // Add our two systems app.add_system(hurt_enemies.before(despawn_dead_enemies)); app.add_system(despawn_dead_enemies); // Setup test entities let enemy_id = app .world .spawn(Enemy { hit_points: 5, score_value: 3, }) .id(); // Run systems app.update(); // Check resulting changes assert!(app.world.get::(enemy_id).is_some()); assert_eq!(app.world.get::(enemy_id).unwrap().hit_points, 4); } #[test] fn did_despawn_enemy() { // Setup app let mut app = App::new(); // Add Score resource app.insert_resource(Score(0)); // Add `EnemyDied` event app.add_event::(); // Add our two systems app.add_system(hurt_enemies.before(despawn_dead_enemies)); app.add_system(despawn_dead_enemies); // Setup test entities let enemy_id = app .world .spawn(Enemy { hit_points: 1, score_value: 1, }) .id(); // Run systems app.update(); // Check enemy was despawned assert!(app.world.get::(enemy_id).is_none()); // Get `EnemyDied` event reader let enemy_died_events = app.world.resource::>(); let mut enemy_died_reader = enemy_died_events.get_reader(); let enemy_died = enemy_died_reader.iter(enemy_died_events).next().unwrap(); // Check the event has been sent assert_eq!(enemy_died.0, 1); } #[test] fn spawn_enemy_using_input_resource() { // Setup app let mut app = App::new(); // Add our systems app.add_system(spawn_enemy); // Setup test resource let mut input = Input::::default(); input.press(KeyCode::Space); app.insert_resource(input); // Run systems app.update(); // Check resulting changes, one entity has been spawned with `Enemy` component assert_eq!(app.world.query::<&Enemy>().iter(&app.world).len(), 1); // Clear the `just_pressed` status for all `KeyCode`s app.world.resource_mut::>().clear(); // Run systems app.update(); // Check resulting changes, no new entity has been spawned assert_eq!(app.world.query::<&Enemy>().iter(&app.world).len(), 1); } #[test] fn update_score_on_event() { // Setup app let mut app = App::new(); // Add Score resource app.insert_resource(Score(0)); // Add `EnemyDied` event app.add_event::(); // Add our systems app.add_system(update_score); // Send an `EnemyDied` event app.world .resource_mut::>() .send(EnemyDied(3)); // Run systems app.update(); // Check resulting changes assert_eq!(app.world.resource::().0, 3); }