Add example of how to use TestPlugin

Cargo.toml

@@ -921,6 +921,16 @@ description = "Illustrates ticking `Timer` resources inside systems and handling
 category = "ECS (Entity Component System)"
 wasm = false
 
+[[example]]
+name = "automated_tests"
+path = "tests/automated_tests.rs"
+
+[package.metadata.example.automated_tests]
+name = "Automated Tests"
+description = "Illustrates how to test systems. Note that this test is in `tests/automated_tests.rs`."
+category = "ECS (Entity Component System)"
+wasm = false
+
 # Games
 [[example]]
 name = "alien_cake_addict"

crates/bevy_internal/src/default_plugins.rs

@@ -81,6 +81,43 @@ impl PluginGroup for DefaultPlugins {
     }
 }
 
+impl DefaultPlugins {
+    /// Usage: `DefaultPlugins::for_testing()`.
+    /// Like DefaultPlugins, but omits some plugins that are likely to be problematic during tests and on CI builds.
+    ///
+    /// * [`RenderPlugin`](bevy_render::RenderPlugin) - with feature `bevy_render`
+    /// * [`SpritePlugin`](bevy_sprite::SpritePlugin) - with feature `bevy_sprite`
+    /// * [`PbrPlugin`](bevy_pbr::PbrPlugin) - with feature `bevy_pbr`
+    /// * [`UiPlugin`](bevy_ui::UiPlugin) - with feature `bevy_ui`
+    /// * [`TextPlugin`](bevy_text::TextPlugin) - with feature `bevy_text`
+    /// * [`AudioPlugin`](bevy_audio::AudioPlugin) - with feature `bevy_audio`
+    /// * [`GltfPlugin`](bevy_gltf::GltfPlugin) - with feature `bevy_gltf`
+    /// * [`WinitPlugin`](bevy_winit::WinitPlugin) - with feature `bevy_winit`
+    ///
+    /// And adds:
+    ///
+    /// * [`ScheduleRunnerPlugin`](bevy_app::ScheduleRunnerPlugin)
+    ///
+    /// Leaving:
+    ///
+    /// * [`CorePlugin`](bevy_core::CorePlugin)
+    /// * [`TimePlugin`](bevy_time::TimePlugin)
+    /// * [`TransformPlugin`](bevy_transform::TransformPlugin)
+    /// * [`HierarchyPlugin`](bevy_hierarchy::HierarchyPlugin)
+    /// * [`DiagnosticsPlugin`](bevy_diagnostic::DiagnosticsPlugin)
+    /// * [`InputPlugin`](bevy_input::InputPlugin)
+    /// * [`WindowPlugin`](bevy_window::WindowPlugin)
+    /// * [`AssetPlugin`](bevy_asset::AssetPlugin)
+    /// * [`ScenePlugin`](bevy_scene::ScenePlugin)
+    /// * [`GilrsPlugin`](bevy_gilrs::GilrsPlugin) - with feature `bevy_gilrs`
+    /// * [`ScheduleRunnerPlugin`](bevy_app::ScheduleRunnerPlugin)
+    ///
+    /// You should probably not use this plugin except in automated tests.
+    pub fn for_testing() -> impl PluginGroup {
+        TestPlugins
+    }
+}
+
 /// Minimal plugin group that will add the following plugins:
 /// * [`CorePlugin`](bevy_core::CorePlugin)
 /// * [`TimePlugin`](bevy_time::TimePlugin)
@@ -97,36 +134,41 @@ impl PluginGroup for MinimalPlugins {
     }
 }
 
+/// Only accessible through `DefaultPlugins::for_testing()`.
 /// Plugin group intended for use in tests, that will add the following plugins:
 /// * [`CorePlugin`](bevy_core::CorePlugin)
 /// * [`TimePlugin`](bevy_time::TimePlugin)
 /// * [`ScheduleRunnerPlugin`](bevy_app::ScheduleRunnerPlugin)
 /// * [`AssetPlugin`](bevy_asset::AssetPlugin)
 /// * [`ScenePlugin`](bevy_scene::ScenePlugin)
 /// * [`WindowPlugin`](bevy_window::WindowPlugin)
-/// * [`RenderPlugin`](bevy_render::RenderPlugin)
-/// * [`GilrsPlugin`](bevy_gilrs::GilrsPlugin)
+/// * [`GilrsPlugin`](bevy_gilrs::GilrsPlugin) - with feature `bevy_gilrs`
 /// * [`TransformPlugin`](bevy_transform::TransformPlugin)
 /// * [`HierarchyPlugin`](bevy_hierarchy::HierarchyPlugin)
 /// * [`DiagnosticsPlugin`](bevy_diagnostic::DiagnosticsPlugin)
 /// * [`InputPlugin`](bevy_input::InputPlugin)
 ///
 /// See also [`DefaultPlugins`] for a more complete set of plugins
-pub struct TestPlugins;
+struct TestPlugins;
 
 impl PluginGroup for TestPlugins {
     fn build(&mut self, group: &mut PluginGroupBuilder) {
         group.add(bevy_core::CorePlugin::default());
         group.add(bevy_time::TimePlugin::default());
         group.add(bevy_app::ScheduleRunnerPlugin::default());
-        group.add(bevy_asset::AssetPlugin);
-        group.add(bevy_scene::ScenePlugin);
         group.add(bevy_window::WindowPlugin);
-        group.add(bevy_render::RenderPlugin);
-        group.add(bevy_gilrs::GilrsPlugin);
         group.add(bevy_transform::TransformPlugin);
         group.add(bevy_hierarchy::HierarchyPlugin);
         group.add(bevy_diagnostic::DiagnosticsPlugin);
         group.add(bevy_input::InputPlugin);
+
+        #[cfg(feature = "bevy_asset")]
+        group.add(bevy_asset::AssetPlugin::default());
+
+        #[cfg(feature = "bevy_scene")]
+        group.add(bevy_scene::ScenePlugin::default());
+
+        #[cfg(feature = "bevy_gilrs")]
+        group.add(bevy_gilrs::GilrsPlugin::default());
     }
 }

crates/bevy_internal/src/prelude.rs

@@ -3,7 +3,6 @@ pub use crate::{
     app::prelude::*, core::prelude::*, ecs::prelude::*, hierarchy::prelude::*, input::prelude::*,
     log::prelude::*, math::prelude::*, reflect::prelude::*, time::prelude::*,
     transform::prelude::*, utils::prelude::*, window::prelude::*, DefaultPlugins, MinimalPlugins,
-    TestPlugins,
 };
 
 pub use bevy_derive::{bevy_main, Deref, DerefMut};

examples/README.md

@@ -187,6 +187,7 @@ Example | Description
 
 Example | Description
 --- | ---
+[Automated Tests](../tests/automated_tests.rs) | Illustrates how to test systems. Note that this test is in `tests/automated_tests.rs`.
 [Component Change Detection](../examples/ecs/component_change_detection.rs) | Change detection on components
 [Custom Query Parameters](../examples/ecs/custom_query_param.rs) | Groups commonly used compound queries and query filters into a single type
 [ECS Guide](../examples/ecs/ecs_guide.rs) | Full guide to Bevy's ECS

tests/automated_tests.rs

@@ -0,0 +1,48 @@
+//! This example illustrates test systems.
+fn main() {
+    println!("This example is special! Run it with `cargo test --example automated_tests`.");
+    println!(
+        "Or use `cargo test --example automated_tests -- --nocapture` to see the debug output."
+    );
+}
+
+#[cfg(test)]
+mod test {
+    use bevy::prelude::*;
+
+    #[test]
+    fn simple_test() {
+        // Setup the app with the TestPlugins – these will run fine in tests and in CI.
+        // Note that many 3rd-party plugins will require DefaultPlugins, not just TestPlugins.
+        let mut app = App::new();
+        app.add_plugins(DefaultPlugins::for_testing()).add_system(increment);
+
+        // Spawn a new entity with a Counter component, and record its ID.
+        let counter_id = app.world.spawn().insert(Counter::default()).id();
+
+        // Simulate for a 10 frames
+        let num_frames = 10;
+        for _ in 0..num_frames {
+            app.update();
+        }
+
+        // Check that the counter was incremented 10 times.
+        let count = app.world.get::<Counter>(counter_id).unwrap().counter;
+        assert_eq!(count, num_frames);
+
+        println!("Success!");
+    }
+    // Define a system and a component that we can use in our test.
+    #[derive(Debug, Default, Component, Clone, Copy)]
+    struct Counter {
+        counter: u64,
+    }
+
+    /// Increment the counter every frame
+    fn increment(mut query: Query<&mut Counter>) {
+        for mut counter in query.iter_mut() {
+            counter.counter += 1;
+            println!("Counter: {}", counter.counter);
+        }
+    }
+}