run some examples on CI using swiftshader (#1826)

From suggestion from Godot workflows: https://github.com/bevyengine/bevy/issues/1730#issuecomment-810321110

* Add a feature `bevy_debug` that will make Bevy read a debug config file to setup some debug systems
  * Currently, only one that will exit after x frames
  * Could add option to dump screen to image file once that's possible
* Add a job in CI workflow that will run a few examples using [`swiftshader`](https://github.com/google/swiftshader)
  * This job takes around 13 minutes, so doesn't add to global CI duration

|example|number of frames|duration|
|-|-|-|
|`alien_cake_addict`|300|1:50|
|`breakout`|1800|0:44|
|`contributors`|1800|0:43|
|`load_gltf`|300|2:37|
|`scene`|1800|0:44|

.github/example-run/alien_cake_addict.ron

@@ -0,0 +1,3 @@
+(
+    exit_after: Some(300)
+)

.github/example-run/breakout.ron

@@ -0,0 +1,3 @@
+(
+    exit_after: Some(1800)
+)

.github/example-run/contributors.ron

@@ -0,0 +1,3 @@
+(
+    exit_after: Some(1800)
+)

.github/example-run/load_gltf.ron

@@ -0,0 +1,3 @@
+(
+    exit_after: Some(300)
+)

.github/example-run/scene.ron

@@ -0,0 +1,3 @@
+(
+    exit_after: Some(1800)
+)

.github/workflows/ci.yml

@@ -92,3 +92,39 @@ jobs:
           DEFAULT_BRANCH: master
           # Not needed here as only one Linter is used.
           #GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  run-examples:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Install dependencies
+        run: |
+          sudo apt-get update;
+          DEBIAN_FRONTEND=noninteractive sudo apt-get install --no-install-recommends -yq \
+            libasound2-dev libudev-dev wget unzip xvfb;
+
+      - uses: actions/checkout@v2
+
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+
+      - name: Setup swiftshader
+        run: |
+          wget https://github.com/qarmin/gtk_library_store/releases/download/3.24.0/swiftshader.zip;
+          unzip swiftshader.zip;
+          curr="$(pwd)/libvk_swiftshader.so";
+          sed -i "s|PATH_TO_CHANGE|$curr|" vk_swiftshader_icd.json;
+
+      - name: Build bevy
+        run: |
+          cargo build --no-default-features --features "bevy_dynamic_plugin,bevy_gilrs,bevy_gltf,bevy_wgpu,bevy_winit,render,png,hdr,x11,bevy_ci_testing"
+
+      - name: Run examples
+        run: |
+          for example in .github/example-run/*.ron; do
+            example_name=`basename $example .ron`
+            echo "running $example_name - "`date`
+            time CI_TESTING_CONFIG=$example VK_ICD_FILENAMES=$(pwd)/vk_swiftshader_icd.json DRI_PRIME=0 xvfb-run cargo run --example $example_name --no-default-features --features "bevy_dynamic_plugin,bevy_gilrs,bevy_gltf,bevy_wgpu,bevy_winit,render,png,hdr,x11,bevy_ci_testing"
+            sleep 10
+          done

Cargo.toml

@@ -75,6 +75,9 @@ x11 = ["bevy_internal/x11"]
 # enable rendering of font glyphs using subpixel accuracy
 subpixel_glyph_atlas = ["bevy_internal/subpixel_glyph_atlas"]
 
+# enable systems that allow for automated testing on CI
+bevy_ci_testing = ["bevy_internal/bevy_ci_testing"]
+
 [dependencies]
 bevy_dylib = {path = "crates/bevy_dylib", version = "0.5.0", default-features = false, optional = true}
 bevy_internal = {path = "crates/bevy_internal", version = "0.5.0", default-features = false}

crates/bevy_app/Cargo.toml

@@ -14,6 +14,7 @@ keywords = ["bevy"]
 
 [features]
 trace = []
+bevy_ci_testing = ["ron"]
 default = ["bevy_reflect"]
 
 [dependencies]
@@ -25,6 +26,8 @@ bevy_utils = { path = "../bevy_utils", version = "0.5.0" }
 
 # other
 serde = { version = "1.0", features = ["derive"] }
+ron = { version = "0.6.2", optional = true }
+
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 wasm-bindgen = { version = "0.2" }

crates/bevy_app/src/app_builder.rs

@@ -33,6 +33,11 @@ impl Default for AppBuilder {
             .add_default_stages()
             .add_event::<AppExit>()
             .add_system_to_stage(CoreStage::Last, World::clear_trackers.exclusive_system());
+
+        #[cfg(feature = "bevy_ci_testing")]
+        {
+            crate::ci_testing::setup_app(&mut app_builder);
+        }
         app_builder
     }
 }

crates/bevy_app/src/ci_testing.rs

@@ -0,0 +1,38 @@
+use serde::Deserialize;
+
+use crate::{app::AppExit, AppBuilder};
+use bevy_ecs::system::IntoSystem;
+
+/// Configuration for automated testing on CI
+#[derive(Deserialize)]
+pub struct CiTestingConfig {
+    /// Number of frames after wich Bevy should exit
+    pub exit_after: Option<u32>,
+}
+
+fn ci_testing_exit_after(
+    mut current_frame: bevy_ecs::prelude::Local<u32>,
+    ci_testing_config: bevy_ecs::prelude::Res<CiTestingConfig>,
+    mut app_exit_events: crate::EventWriter<AppExit>,
+) {
+    if let Some(exit_after) = ci_testing_config.exit_after {
+        if *current_frame > exit_after {
+            app_exit_events.send(AppExit);
+        }
+    }
+    *current_frame += 1;
+}
+
+pub(crate) fn setup_app(app_builder: &mut AppBuilder) -> &mut AppBuilder {
+    let filename =
+        std::env::var("CI_TESTING_CONFIG").unwrap_or_else(|_| "ci_testing_config.ron".to_string());
+    let config: CiTestingConfig = ron::from_str(
+        &std::fs::read_to_string(filename).expect("error reading CI testing configuration file"),
+    )
+    .expect("error deserializing CI testing configuration file");
+    app_builder
+        .insert_resource(config)
+        .add_system(ci_testing_exit_after.system());
+
+    app_builder
+}

crates/bevy_app/src/lib.rs

@@ -4,6 +4,9 @@ mod plugin;
 mod plugin_group;
 mod schedule_runner;
 
+#[cfg(feature = "bevy_ci_testing")]
+mod ci_testing;
+
 pub use app::*;
 pub use app_builder::*;
 pub use bevy_derive::DynamicPlugin;

crates/bevy_internal/Cargo.toml

@@ -41,6 +41,9 @@ x11 = ["bevy_winit/x11"]
 # enable rendering of font glyphs using subpixel accuracy
 subpixel_glyph_atlas = ["bevy_text/subpixel_glyph_atlas"]
 
+# enable systems that allow for automated testing on CI
+bevy_ci_testing = ["bevy_app/bevy_ci_testing"]
+
 [dependencies]
 # bevy
 bevy_app = { path = "../bevy_app", version = "0.5.0" }