Only Initialize a Single Backend in Tests

tests/src/init.rs

@@ -1,6 +1,8 @@
 use wgpu::{Adapter, Device, Instance, Queue};
 use wgt::{Backends, Features, Limits};
 
+use crate::report::AdapterReport;
+
 /// Initialize the logger for the test runner.
 pub fn init_logger() {
     // We don't actually care if it fails
@@ -11,7 +13,7 @@ pub fn init_logger() {
 }
 
 /// Initialize a wgpu instance with the options from the environment.
-pub fn initialize_instance(force_fxc: bool) -> Instance {
+pub fn initialize_instance(backends: wgpu::Backends, force_fxc: bool) -> Instance {
     // We ignore `WGPU_BACKEND` for now, merely using test filtering to only run a single backend's tests.
     //
     // We can potentially work support back into the test runner in the future, but as the adapters are matched up
@@ -23,9 +25,9 @@ pub fn initialize_instance(force_fxc: bool) -> Instance {
     // To "disable" webgpu regardless, we do this by removing the webgpu backend whenever we see
     // the webgl feature.
     let backends = if cfg!(feature = "webgl") {
-        Backends::all() - Backends::BROWSER_WEBGPU
+        backends - wgpu::Backends::BROWSER_WEBGPU
     } else {
-        Backends::all()
+        backends
     };
     // Some tests need to be able to force demote to FXC, to specifically test workarounds for FXC
     // behavior.
@@ -43,12 +45,16 @@ pub fn initialize_instance(force_fxc: bool) -> Instance {
     })
 }
 
-/// Initialize a wgpu adapter, taking the `n`th adapter from the instance.
+/// Initialize a wgpu adapter, using the given adapter report to match the adapter.
 pub async fn initialize_adapter(
-    adapter_index: usize,
+    adapter_report: Option<&AdapterReport>,
     force_fxc: bool,
 ) -> (Instance, Adapter, Option<SurfaceGuard>) {
-    let instance = initialize_instance(force_fxc);
+    let backends = adapter_report
+        .map(|report| Backends::from(report.info.backend))
+        .unwrap_or_default();
+
+    let instance = initialize_instance(backends, force_fxc);
     #[allow(unused_variables)]
     let surface: Option<wgpu::Surface>;
     let surface_guard: Option<SurfaceGuard>;
@@ -82,13 +88,24 @@ pub async fn initialize_adapter(
 
     cfg_if::cfg_if! {
         if #[cfg(not(target_arch = "wasm32"))] {
-            let adapter_iter = instance.enumerate_adapters(wgpu::Backends::all());
-            let adapter_count = adapter_iter.len();
+            let adapter_iter = instance.enumerate_adapters(backends);
             let adapter = adapter_iter.into_iter()
-                .nth(adapter_index)
-                .unwrap_or_else(|| panic!("Tried to get index {adapter_index} adapter, but adapter list was only {adapter_count} long. Is .gpuconfig out of date?"));
+                // If we have a report, we only want to match the adapter with the same info.
+                //
+                // If we don't have a report, we just take the first adapter.
+                .find(|adapter| if let Some(adapter_report) = adapter_report {
+                    adapter.get_info() == adapter_report.info
+                } else {
+                    true
+                });
+            let Some(adapter) = adapter else {
+                panic!(
+                    "Could not find adapter with info {:#?} in {:#?}",
+                    adapter_report.map(|r| &r.info),
+                    instance.enumerate_adapters(backends).into_iter().map(|a| a.get_info()).collect::<Vec<_>>(),
+                );
+            };
         } else {
-            assert_eq!(adapter_index, 0);
             let adapter = instance.request_adapter(&wgpu::RequestAdapterOptions {
                 compatible_surface: surface.as_ref(),
                 ..Default::default()

tests/src/native.rs

@@ -19,15 +19,16 @@ struct NativeTest {
 }
 
 impl NativeTest {
+    /// Adapter index is only used for naming the test, the adapters are matched based on the adapter info.
     fn from_configuration(
         config: GpuTestConfiguration,
-        adapter: &AdapterReport,
+        adapter_report: AdapterReport,
         adapter_index: usize,
     ) -> Self {
-        let backend = adapter.info.backend;
-        let device_name = &adapter.info.name;
+        let backend = adapter_report.info.backend;
+        let device_name = &adapter_report.info.name;
 
-        let test_info = TestInfo::from_configuration(&config, adapter);
+        let test_info = TestInfo::from_configuration(&config, &adapter_report);
 
         let full_name = format!(
             "[{running_msg}] [{backend:?}/{device_name}/{adapter_index}] {base_name}",
@@ -50,10 +51,12 @@ impl NativeTest {
 
                 let env_value = if metal_validation { "1" } else { "0" };
                 std::env::set_var("MTL_DEBUG_LAYER", env_value);
-                // Metal Shader Validation is entirely broken in the paravirtualized CI environment.
-                // std::env::set_var("MTL_SHADER_VALIDATION", env_value);
+                if std::env::var("GITHUB_ACTIONS").as_deref() != Ok("true") {
+                    // Metal Shader Validation is entirely broken in the paravirtualized CI environment.
+                    std::env::set_var("MTL_SHADER_VALIDATION", env_value);
+                }
 
-                execute_test(config, Some(test_info), adapter_index).await;
+                execute_test(Some(&adapter_report), config, Some(test_info)).await;
             }),
         }
     }
@@ -83,16 +86,24 @@ pub fn main() -> MainResult {
         &std::fs::read_to_string(format!("{}/../.gpuconfig", env!("CARGO_MANIFEST_DIR")))
             .context("Failed to read .gpuconfig, did you run the tests via `cargo xtask test`?")?
     };
-    let report = GpuReport::from_json(config_text).context("Could not parse .gpuconfig JSON")?;
+    let mut report =
+        GpuReport::from_json(config_text).context("Could not parse .gpuconfig JSON")?;
+
+    // Filter out the adapters that are not part of WGPU_BACKEND.
+    let wgpu_backends = wgpu::util::backend_bits_from_env().unwrap_or(wgpu::Backends::all());
+    report
+        .devices
+        .retain(|report| wgpu_backends.contains(wgpu::Backends::from(report.info.backend)));
 
     let mut test_guard = TEST_LIST.lock();
+    // Iterate through all the tests. Creating a test per adapter.
     execute_native(test_guard.drain(..).flat_map(|test| {
         report
             .devices
             .iter()
             .enumerate()
-            .map(move |(adapter_index, adapter)| {
-                NativeTest::from_configuration(test.clone(), adapter, adapter_index)
+            .map(move |(adapter_index, adapter_report)| {
+                NativeTest::from_configuration(test.clone(), adapter_report.clone(), adapter_index)
             })
     }));
 

tests/src/report.rs

@@ -25,8 +25,8 @@ impl GpuReport {
 /// A single report of the capabilities of an Adapter.
 ///
 /// Must be synchronized with the definition on wgpu-info/src/report.rs.
-#[derive(Deserialize)]
-pub(crate) struct AdapterReport {
+#[derive(Deserialize, Clone)]
+pub struct AdapterReport {
     pub info: AdapterInfo,
     pub features: Features,
     pub limits: Limits,

tests/src/run.rs

@@ -24,14 +24,14 @@ pub struct TestingContext {
     pub queue: Queue,
 }
 
-/// Execute the given test configuration with the given adapter index.
+/// Execute the given test configuration with the given adapter report.
 ///
 /// If test_info is specified, will use the information whether to skip the test.
 /// If it is not, we'll create the test info from the adapter itself.
 pub async fn execute_test(
+    adapter_report: Option<&AdapterReport>,
     config: GpuTestConfiguration,
     test_info: Option<TestInfo>,
-    adapter_index: usize,
 ) {
     // If we get information externally, skip based on that information before we do anything.
     if let Some(TestInfo { skip: true, .. }) = test_info {
@@ -43,7 +43,7 @@ pub async fn execute_test(
     let _test_guard = isolation::OneTestPerProcessGuard::new();
 
     let (instance, adapter, _surface_guard) =
-        initialize_adapter(adapter_index, config.params.force_fxc).await;
+        initialize_adapter(adapter_report, config.params.force_fxc).await;
 
     let adapter_info = adapter.get_info();
     let adapter_downlevel_capabilities = adapter.get_downlevel_capabilities();

tests/tests/device.rs

@@ -87,7 +87,7 @@ static REQUEST_DEVICE_ERROR_MESSAGE_NATIVE: GpuTestConfiguration =
 async fn request_device_error_message() {
     // Not using initialize_test() because that doesn't let us catch the error
     // nor .await anything
-    let (_instance, adapter, _surface_guard) = wgpu_test::initialize_adapter(0, false).await;
+    let (_instance, adapter, _surface_guard) = wgpu_test::initialize_adapter(None, false).await;
 
     let device_error = adapter
         .request_device(

wgpu-macros/src/lib.rs

@@ -37,7 +37,7 @@ pub fn gpu_test(_attr: TokenStream, item: TokenStream) -> TokenStream {
             // Allow any type that can be converted to a GpuTestConfiguration
             let test_config = ::wgpu_test::GpuTestConfiguration::from(#expr).name_from_init_function_typename::<S>(#ident_lower);
 
-            ::wgpu_test::execute_test(test_config, None, 0).await;
+            ::wgpu_test::execute_test(None, test_config, None).await;
         }
     }
     .into()