bevy/tests/how_to_test_systems.rs
Paweł Grabarz 07ed1d053e Implement and require #[derive(Component)] on all component structs (#2254)
This implements the most minimal variant of #1843 - a derive for marker trait. This is a prerequisite to more complicated features like statically defined storage type or opt-out component reflection.

In order to make component struct's purpose explicit and avoid misuse, it must be annotated with `#[derive(Component)]` (manual impl is discouraged for compatibility). Right now this is just a marker trait, but in the future it might be expanded. Making this change early allows us to make further changes later without breaking backward compatibility for derive macro users.

This already prevents a lot of issues, like using bundles in `insert` calls. Primitive types are no longer valid components as well. This can be easily worked around by adding newtype wrappers and deriving `Component` for them.

One funny example of prevented bad code (from our own tests) is when an newtype struct or enum variant is used. Previously, it was possible to write `insert(Newtype)` instead of `insert(Newtype(value))`. That code compiled, because function pointers (in this case newtype struct constructor) implement `Send + Sync + 'static`, so we allowed them to be used as components. This is no longer the case and such invalid code will trigger a compile error.


Co-authored-by: = <=>
Co-authored-by: TheRawMeatball <therawmeatball@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2021-10-03 19:23:44 +00:00

97 lines
2.6 KiB
Rust

use bevy::prelude::*;
#[derive(Component, Default)]
struct Enemy {
hit_points: u32,
}
fn despawn_dead_enemies(mut commands: Commands, enemies: Query<(Entity, &Enemy)>) {
for (entity, enemy) in enemies.iter() {
if enemy.hit_points == 0 {
commands.entity(entity).despawn_recursive();
}
}
}
fn hurt_enemies(mut enemies: Query<&mut Enemy>) {
for mut enemy in enemies.iter_mut() {
enemy.hit_points -= 1;
}
}
fn spawn_enemy(mut commands: Commands, keyboard_input: Res<Input<KeyCode>>) {
if keyboard_input.just_pressed(KeyCode::Space) {
commands.spawn().insert(Enemy { hit_points: 5 });
}
}
#[test]
fn did_hurt_enemy() {
// Setup world
let mut world = World::default();
// Setup stage with our two systems
let mut update_stage = SystemStage::parallel();
update_stage.add_system(hurt_enemies.before("death"));
update_stage.add_system(despawn_dead_enemies.label("death"));
// Setup test entities
let enemy_id = world.spawn().insert(Enemy { hit_points: 5 }).id();
// Run systems
update_stage.run(&mut world);
// Check resulting changes
assert!(world.get::<Enemy>(enemy_id).is_some());
assert_eq!(world.get::<Enemy>(enemy_id).unwrap().hit_points, 4);
}
#[test]
fn did_despawn_enemy() {
// Setup world
let mut world = World::default();
// Setup stage with our two systems
let mut update_stage = SystemStage::parallel();
update_stage.add_system(hurt_enemies.before("death"));
update_stage.add_system(despawn_dead_enemies.label("death"));
// Setup test entities
let enemy_id = world.spawn().insert(Enemy { hit_points: 1 }).id();
// Run systems
update_stage.run(&mut world);
// Check resulting changes
assert!(world.get::<Enemy>(enemy_id).is_none());
}
#[test]
fn spawn_enemy_using_input_resource() {
// Setup world
let mut world = World::default();
// Setup stage with a system
let mut update_stage = SystemStage::parallel();
update_stage.add_system(spawn_enemy);
// Setup test resource
let mut input = Input::<KeyCode>::default();
input.press(KeyCode::Space);
world.insert_resource(input);
// Run systems
update_stage.run(&mut world);
// Check resulting changes, one entity has been spawned with `Enemy` component
assert_eq!(world.query::<&Enemy>().iter(&world).len(), 1);
// Clear the `just_pressed` status for all `KeyCode`s
world.get_resource_mut::<Input<KeyCode>>().unwrap().clear();
// Run systems
update_stage.run(&mut world);
// Check resulting changes, no new entity has been spawned
assert_eq!(world.query::<&Enemy>().iter(&world).len(), 1);
}