use bevy::{ecs::event::Events, prelude::*};
#[derive(Component, Default)]
struct Enemy {
hit_points: u32,
score_value: u32,
}
#[derive(Event)]
struct EnemyDied(u32);
#[derive(Resource)]
struct Score(u32);
fn update_score(mut dead_enemies: EventReader<EnemyDied>, mut score: ResMut<Score>) {
for value in dead_enemies.read() {
score.0 += value.0;
}
}
fn despawn_dead_enemies(
mut commands: Commands,
mut dead_enemies: EventWriter<EnemyDied>,
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<ButtonInput<KeyCode>>) {
if keyboard_input.just_pressed(KeyCode::Space) {
commands.spawn(Enemy {
hit_points: 5,
score_value: 3,
});
}
}
#[test]
fn did_hurt_enemy() {
let mut app = App::new();
app.insert_resource(Score(0));
app.add_event::<EnemyDied>();
app.add_systems(Update, (hurt_enemies, despawn_dead_enemies).chain());
let enemy_id = app
.world
.spawn(Enemy {
hit_points: 5,
score_value: 3,
})
.id();
app.update();
assert!(app.world.get::<Enemy>(enemy_id).is_some());
assert_eq!(app.world.get::<Enemy>(enemy_id).unwrap().hit_points, 4);
}
#[test]
fn did_despawn_enemy() {
let mut app = App::new();
app.insert_resource(Score(0));
app.add_event::<EnemyDied>();
app.add_systems(Update, (hurt_enemies, despawn_dead_enemies).chain());
let enemy_id = app
.world
.spawn(Enemy {
hit_points: 1,
score_value: 1,
})
.id();
app.update();
assert!(app.world.get::<Enemy>(enemy_id).is_none());
let enemy_died_events = app.world.resource::<Events<EnemyDied>>();
let mut enemy_died_reader = enemy_died_events.get_reader();
let enemy_died = enemy_died_reader.read(enemy_died_events).next().unwrap();
assert_eq!(enemy_died.0, 1);
}
#[test]
fn spawn_enemy_using_input_resource() {
let mut app = App::new();
app.add_systems(Update, spawn_enemy);
let mut input = ButtonInput::<KeyCode>::default();
input.press(KeyCode::Space);
app.insert_resource(input);
app.update();
assert_eq!(app.world.query::<&Enemy>().iter(&app.world).len(), 1);
app.world.resource_mut::<ButtonInput<KeyCode>>().clear();
app.update();
assert_eq!(app.world.query::<&Enemy>().iter(&app.world).len(), 1);
}
#[test]
fn update_score_on_event() {
let mut app = App::new();
app.insert_resource(Score(0));
app.add_event::<EnemyDied>();
app.add_systems(Update, update_score);
app.world
.resource_mut::<Events<EnemyDied>>()
.send(EnemyDied(3));
app.update();
assert_eq!(app.world.resource::<Score>().0, 3);
}