src/lib/fuchsia-async/src/test_support.rs - fuchsia - Git at Google

 // Copyright 2020 The Fuchsia Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 use crate::TimeoutExt;
 use futures::{lock::Mutex, prelude::*};
 use std::pin::Pin;
 use std::sync::Arc;
 use std::time::Duration;
 #[cfg(target_os = "fuchsia")]
 use std::{pin::pin, task::Poll};

 // Apply the timeout from config to test
 // Ideally this would be a function like Config::with_timeout, but we need to handle Send and !Send
 // and it's likely better not to have to duplicate this code.
 macro_rules! apply_timeout {
     ($config:expr, $test:expr) => {{
         let timeout = $config.timeout;
         let test = $test;
         move |run| {
             let test = test(run);
             async move {
                 if let Some(timeout) = timeout {
                     test.on_timeout(timeout, || panic!("timeout on run {}", run)).await
                 } else {
                     test.await
                 }
             }
         }
     }};
 }

 /// Defines how to compose multiple test runs for a kind of test result.
 pub trait TestResult: Sized {
     /// How to repeatedly run a test with this result in a single threaded executor.
     fn run_singlethreaded(
         test: Arc<dyn Send + Sync + Fn(usize) -> Pin<Box<dyn Future<Output = Self>>>>,
         cfg: Config,
     ) -> Self;

     /// Similarly, but use run_until_stalled
     #[cfg(target_os = "fuchsia")]
     fn run_until_stalled<F: 'static + Fn(usize) -> Fut, Fut: 'static + Future<Output = Self>>(
         executor: &mut crate::TestExecutor,
         test: F,
         cfg: Config,
     ) -> Poll<Self>;
 }

 /// Defines how to compose multiple test runs for a kind of test result in a multithreaded executor.
 pub trait MultithreadedTestResult: Sized {
     /// How to repeatedly run a test with this result in a multi threaded executor.
     fn run<F: 'static + Send + Fn(usize) -> Fut, Fut: 'static + Send + Future<Output = Self>>(
         test: F,
         threads: usize,
         cfg: Config,
     ) -> Self;
 }

 impl<E: 'static + std::fmt::Debug> TestResult for Result<(), E> {
     fn run_singlethreaded(
         test: Arc<dyn Send + Sync + Fn(usize) -> Pin<Box<dyn Future<Output = Self>>>>,
         cfg: Config,
     ) -> Self {
         let run_stream = Arc::new(Mutex::new(stream::iter(0..cfg.repeat_count).fuse()));
         let test = apply_timeout!(cfg, test);
         cfg.in_parallel(Arc::new(move || {
             let run_stream = run_stream.clone();
             let test = test.clone();
             crate::LocalExecutor::new().run_singlethreaded(async move {
                 while let Some(run) = run_stream.lock().await.next().await {
                     if let Err(e) = test(run).await {
                         panic!("run {} failed with error {:?}", run, e)
                     }
                 }
             })
         }));
         Ok(())
     }

     #[cfg(target_os = "fuchsia")]
     fn run_until_stalled<F: 'static + Fn(usize) -> Fut, Fut: 'static + Future<Output = Self>>(
         executor: &mut crate::TestExecutor,
         test: F,
         cfg: Config,
     ) -> Poll<Self> {
         executor.run_until_stalled(
             &mut stream::iter(0..cfg.repeat_count)
                 .map(Ok)
                 .try_for_each_concurrent(cfg.max_concurrency, apply_timeout!(cfg, test)),
         )
     }
 }

 impl<E: 'static + Send> MultithreadedTestResult for Result<(), E> {
     fn run<F: 'static + Send + Fn(usize) -> Fut, Fut: 'static + Send + Future<Output = Self>>(
         test: F,
         threads: usize,
         cfg: Config,
     ) -> Self {
         crate::SendExecutor::new(cfg.scale_threads(threads)).run(
             stream::iter(0..cfg.repeat_count)
                 .map(Ok)
                 .try_for_each_concurrent(cfg.max_concurrency, apply_timeout!(cfg, test)),
         )
     }
 }

 impl TestResult for () {
     fn run_singlethreaded(
         test: Arc<dyn Send + Sync + Fn(usize) -> Pin<Box<dyn Future<Output = Self>>>>,
         cfg: Config,
     ) -> Self {
         let run_stream = Arc::new(Mutex::new(stream::iter(0..cfg.repeat_count).fuse()));
         let test = apply_timeout!(cfg, Arc::new(test));
         cfg.in_parallel(Arc::new(move || {
             let run_stream = run_stream.clone();
             let test = test.clone();
             crate::LocalExecutor::new().run_singlethreaded(async move {
                 while let Some(run) = run_stream.lock().await.next().await {
                     test(run).await;
                 }
             })
         }));
     }

     #[cfg(target_os = "fuchsia")]
     fn run_until_stalled<F: 'static + Fn(usize) -> Fut, Fut: 'static + Future<Output = Self>>(
         executor: &mut crate::TestExecutor,
         test: F,
         cfg: Config,
     ) -> Poll<Self> {
         // TODO(ctiller): figure out why this is necessary and unify the loops
         if cfg.repeat_count == 1 {
             let mut test = pin!(test(1));
             executor.run_until_stalled(&mut test)
         } else {
             executor.run_until_stalled(
                 &mut stream::iter(0..cfg.repeat_count)
                     .for_each_concurrent(cfg.max_concurrency, apply_timeout!(cfg, test)),
             )
         }
     }
 }

 impl MultithreadedTestResult for () {
     fn run<F: 'static + Send + Fn(usize) -> Fut, Fut: 'static + Send + Future<Output = Self>>(
         test: F,
         threads: usize,
         cfg: Config,
     ) -> Self {
         crate::SendExecutor::new(cfg.scale_threads(threads)).run(
             stream::iter(0..cfg.repeat_count)
                 .for_each_concurrent(cfg.max_concurrency, apply_timeout!(cfg, test)),
         )
     }
 }

 /// Configuration variables for a single test run.
 #[derive(Clone)]
 pub struct Config {
     repeat_count: usize,
     max_concurrency: usize,
     max_threads: usize,
     timeout: Option<Duration>,
 }

 fn env_var<T: std::str::FromStr>(name: &str, default: T) -> T {
     std::env::var(name).unwrap_or_default().parse().unwrap_or(default)
 }

 impl Config {
     fn get() -> Self {
         let repeat_count = std::cmp::max(1, env_var("FASYNC_TEST_REPEAT_COUNT", 1));
         let max_concurrency = env_var("FASYNC_TEST_MAX_CONCURRENCY", 0);
         let timeout_seconds = env_var("FASYNC_TEST_TIMEOUT_SECONDS", 0);
         let max_threads = env_var("FASYNC_TEST_MAX_THREADS", 0);
         let timeout =
             if timeout_seconds == 0 { None } else { Some(Duration::from_secs(timeout_seconds)) };
         Self { repeat_count, max_concurrency, max_threads, timeout }
     }

     // Scale a hard-coded thread count by some factor to account for increased concurrency in the config.
     fn scale_threads(&self, test_threads: usize) -> usize {
         // We try to scale up by the maximum concurrency we'll see.
         let scale = if self.max_concurrency == 0 {
             // If concurrency is unbounded, we'll see a maximum of the test repetitions.
             self.repeat_count
         } else {
             // Otherwise the maximum concurrency will be the lower of repeat count and the concurrency cap.
             std::cmp::min(self.repeat_count, self.max_concurrency)
         };
         // Without resource constraints, we'd like to run with our test threads scaled up by the cooncurrency.
         let desired_threads = test_threads * scale;
         // Account for resource constraints
         let capped_threads = if self.max_threads == 0 {
             desired_threads
         } else {
             std::cmp::min(desired_threads, self.max_threads)
         };
         // Always run *AT LEAST* the typed in number of threads in the test definition.
         std::cmp::max(capped_threads, test_threads)
     }

     fn in_parallel(&self, f: Arc<dyn 'static + Send + Sync + Fn()>) {
         // N-1 background threads...
         let threads: Vec<_> = std::iter::repeat_with(|| {
             let f = f.clone();
             std::thread::spawn(move || f())
         })
         .take(self.scale_threads(1) - 1)
         .collect();
         // ... and we'll consume this thread to get to N.
         f();
         threads.into_iter().for_each(|t| t.join().expect("worker threads should be joinable"));
     }
 }

 /// Runs a test in an executor, potentially repeatedly and concurrently
 pub fn run_singlethreaded_test<F, Fut, R>(test: F) -> R
 where
     F: 'static + Send + Sync + Fn(usize) -> Fut,
     Fut: 'static + Future<Output = R>,
     R: TestResult,
 {
     TestResult::run_singlethreaded(Arc::new(move |run| test(run).boxed_local()), Config::get())
 }

 /// Runs a test in an executor until it's stalled
 #[cfg(target_os = "fuchsia")]
 pub fn run_until_stalled_test<F, Fut, R>(executor: &mut crate::TestExecutor, test: F) -> R
 where
     F: 'static + Fn(usize) -> Fut,
     Fut: 'static + Future<Output = R>,
     R: TestResult,
 {
     match TestResult::run_until_stalled(executor, test, Config::get()) {
         Poll::Ready(result) => result,
         _ => panic!(
             "Stalled without completing. Consider using \"run_singlethreaded\", or check for a deadlock."
         ),
     }
 }

 /// Runs a test in an executor, potentially repeatedly and concurrently
 pub fn run_test<F, Fut, R>(test: F, threads: usize) -> R
 where
     F: 'static + Send + Fn(usize) -> Fut,
     Fut: 'static + Send + Future<Output = R>,
     R: MultithreadedTestResult,
 {
     MultithreadedTestResult::run(test, threads, Config::get())
 }

 #[cfg(test)]
 mod tests {
     use super::{Config, MultithreadedTestResult, TestResult};
     use futures::lock::Mutex;
     use futures::prelude::*;
     use std::collections::HashSet;
     use std::sync::Arc;
     use std::time::Duration;

     #[test]
     fn scale_threads() {
         let cfg = |repeat_count, max_concurrency, max_threads| Config {
             repeat_count,
             max_concurrency,
             max_threads,
             timeout: None,
         };
         // Unbounded work should look like tests_per_thread * repeat_count
         assert_eq!(cfg(1, 0, 0).scale_threads(1), 1);
         assert_eq!(cfg(1, 0, 0).scale_threads(20), 20);
         assert_eq!(cfg(30, 0, 0).scale_threads(1), 30);
         assert_eq!(cfg(30, 0, 0).scale_threads(20), 600);
         // Max concurrency should affect repetition count
         assert_eq!(cfg(30, 1, 0).scale_threads(20), 20);
         // Capping thread count should not decrease programmatic maximum
         assert_eq!(cfg(1, 0, 5).scale_threads(10), 10);
         assert_eq!(cfg(1, 0, 15).scale_threads(10), 10);
     }

     #[test]
     fn run_singlethreaded() {
         const REPEAT_COUNT: usize = 1000;
         const MAX_THREADS: usize = 10;
         let pending_runs: Arc<Mutex<HashSet<_>>> =
             Arc::new(Mutex::new((0..REPEAT_COUNT).collect()));
         let pending_runs_child = pending_runs.clone();
         TestResult::run_singlethreaded(
             Arc::new(move |i| {
                 let pending_runs_child = pending_runs_child.clone();
                 async move {
                     assert!(pending_runs_child.lock().await.remove(&i));
                 }
                 .boxed_local()
             }),
             Config {
                 repeat_count: REPEAT_COUNT,
                 max_concurrency: 0,
                 max_threads: MAX_THREADS,
                 timeout: None,
             },
         );
         assert!(pending_runs.try_lock().unwrap().is_empty());
     }

     // TODO(https://fxbug.dev/42138715): should_panic tests trigger LSAN
     #[ignore]
     #[test]
     #[should_panic]
     fn run_singlethreaded_with_timeout() {
         TestResult::run_singlethreaded(
             Arc::new(move |_| {
                 async move {
                     futures::future::pending::<()>().await;
                 }
                 .boxed_local()
             }),
             Config {
                 repeat_count: 1,
                 max_concurrency: 0,
                 max_threads: 0,
                 timeout: Some(Duration::from_millis(1)),
             },
         );
     }

     #[test]
     #[cfg(target_os = "fuchsia")]
     fn run_until_stalled() {
         const REPEAT_COUNT: usize = 1000;
         let pending_runs: Arc<Mutex<HashSet<_>>> =
             Arc::new(Mutex::new((0..REPEAT_COUNT).collect()));
         let pending_runs_child = pending_runs.clone();
         match TestResult::run_until_stalled(
             &mut crate::TestExecutor::new(),
             move |i| {
                 let pending_runs_child = pending_runs_child.clone();
                 async move {
                     assert!(pending_runs_child.lock().await.remove(&i));
                 }
             },
             Config {
                 repeat_count: REPEAT_COUNT,
                 max_concurrency: 1,
                 max_threads: 1,
                 timeout: None,
             },
         ) {
             std::task::Poll::Ready(()) => (),
             _ => panic!("Expected everything stalled"),
         }
         assert!(pending_runs.try_lock().unwrap().is_empty());
     }

     #[test]
     fn run() {
         const REPEAT_COUNT: usize = 1000;
         const THREADS: usize = 4;
         let pending_runs: Arc<Mutex<HashSet<_>>> =
             Arc::new(Mutex::new((0..REPEAT_COUNT).collect()));
         let pending_runs_child = pending_runs.clone();
         MultithreadedTestResult::run(
             move |i| {
                 let pending_runs_child = pending_runs_child.clone();
                 async move {
                     assert!(pending_runs_child.lock().await.remove(&i));
                 }
             },
             THREADS,
             Config {
                 repeat_count: REPEAT_COUNT,
                 max_concurrency: 0,
                 max_threads: THREADS,
                 timeout: None,
             },
         );
         assert!(pending_runs.try_lock().unwrap().is_empty());
     }

     // TODO(https://fxbug.dev/42138715): should_panic tests trigger LSAN
     #[ignore]
     #[test]
     #[should_panic]
     fn run_with_timeout() {
         const THREADS: usize = 4;
         MultithreadedTestResult::run(
             move |_| async move {
                 futures::future::pending::<()>().await;
             },
             THREADS,
             Config {
                 repeat_count: 1,
                 max_concurrency: 0,
                 max_threads: 0,
                 timeout: Some(Duration::from_millis(1)),
             },
         );
     }
 }
	// Copyright 2020 The Fuchsia Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	use crate::TimeoutExt;
	use futures::{lock::Mutex, prelude::*};
	use std::pin::Pin;
	use std::sync::Arc;
	use std::time::Duration;
	#[cfg(target_os = "fuchsia")]
	use std::{pin::pin, task::Poll};

	// Apply the timeout from config to test
	// Ideally this would be a function like Config::with_timeout, but we need to handle Send and !Send
	// and it's likely better not to have to duplicate this code.
	macro_rules! apply_timeout {
	($config:expr, $test:expr) => {{
	let timeout = $config.timeout;
	let test = $test;
	move \|run\| {
	let test = test(run);
	async move {
	if let Some(timeout) = timeout {
	test.on_timeout(timeout, \|\| panic!("timeout on run {}", run)).await
	} else {
	test.await
	}
	}
	}
	}};
	}

	/// Defines how to compose multiple test runs for a kind of test result.
	pub trait TestResult: Sized {
	/// How to repeatedly run a test with this result in a single threaded executor.
	fn run_singlethreaded(
	test: Arc<dyn Send + Sync + Fn(usize) -> Pin<Box<dyn Future<Output = Self>>>>,
	cfg: Config,
	) -> Self;

	/// Similarly, but use run_until_stalled
	#[cfg(target_os = "fuchsia")]
	fn run_until_stalled<F: 'static + Fn(usize) -> Fut, Fut: 'static + Future<Output = Self>>(
	executor: &mut crate::TestExecutor,
	test: F,
	cfg: Config,
	) -> Poll<Self>;
	}

	/// Defines how to compose multiple test runs for a kind of test result in a multithreaded executor.
	pub trait MultithreadedTestResult: Sized {
	/// How to repeatedly run a test with this result in a multi threaded executor.
	fn run<F: 'static + Send + Fn(usize) -> Fut, Fut: 'static + Send + Future<Output = Self>>(
	test: F,
	threads: usize,
	cfg: Config,
	) -> Self;
	}

	impl<E: 'static + std::fmt::Debug> TestResult for Result<(), E> {
	fn run_singlethreaded(
	test: Arc<dyn Send + Sync + Fn(usize) -> Pin<Box<dyn Future<Output = Self>>>>,
	cfg: Config,
	) -> Self {
	let run_stream = Arc::new(Mutex::new(stream::iter(0..cfg.repeat_count).fuse()));
	let test = apply_timeout!(cfg, test);
	cfg.in_parallel(Arc::new(move \|\| {
	let run_stream = run_stream.clone();
	let test = test.clone();
	crate::LocalExecutor::new().run_singlethreaded(async move {
	while let Some(run) = run_stream.lock().await.next().await {
	if let Err(e) = test(run).await {
	panic!("run {} failed with error {:?}", run, e)
	}
	}
	})
	}));
	Ok(())
	}

	#[cfg(target_os = "fuchsia")]
	fn run_until_stalled<F: 'static + Fn(usize) -> Fut, Fut: 'static + Future<Output = Self>>(
	executor: &mut crate::TestExecutor,
	test: F,
	cfg: Config,
	) -> Poll<Self> {
	executor.run_until_stalled(
	&mut stream::iter(0..cfg.repeat_count)
	.map(Ok)
	.try_for_each_concurrent(cfg.max_concurrency, apply_timeout!(cfg, test)),
	)
	}
	}

	impl<E: 'static + Send> MultithreadedTestResult for Result<(), E> {
	fn run<F: 'static + Send + Fn(usize) -> Fut, Fut: 'static + Send + Future<Output = Self>>(
	test: F,
	threads: usize,
	cfg: Config,
	) -> Self {
	crate::SendExecutor::new(cfg.scale_threads(threads)).run(
	stream::iter(0..cfg.repeat_count)
	.map(Ok)
	.try_for_each_concurrent(cfg.max_concurrency, apply_timeout!(cfg, test)),
	)
	}
	}

	impl TestResult for () {
	fn run_singlethreaded(
	test: Arc<dyn Send + Sync + Fn(usize) -> Pin<Box<dyn Future<Output = Self>>>>,
	cfg: Config,
	) -> Self {
	let run_stream = Arc::new(Mutex::new(stream::iter(0..cfg.repeat_count).fuse()));
	let test = apply_timeout!(cfg, Arc::new(test));
	cfg.in_parallel(Arc::new(move \|\| {
	let run_stream = run_stream.clone();
	let test = test.clone();
	crate::LocalExecutor::new().run_singlethreaded(async move {
	while let Some(run) = run_stream.lock().await.next().await {
	test(run).await;
	}
	})
	}));
	}

	#[cfg(target_os = "fuchsia")]
	fn run_until_stalled<F: 'static + Fn(usize) -> Fut, Fut: 'static + Future<Output = Self>>(
	executor: &mut crate::TestExecutor,
	test: F,
	cfg: Config,
	) -> Poll<Self> {
	// TODO(ctiller): figure out why this is necessary and unify the loops
	if cfg.repeat_count == 1 {
	let mut test = pin!(test(1));
	executor.run_until_stalled(&mut test)
	} else {
	executor.run_until_stalled(
	&mut stream::iter(0..cfg.repeat_count)
	.for_each_concurrent(cfg.max_concurrency, apply_timeout!(cfg, test)),
	)
	}
	}
	}

	impl MultithreadedTestResult for () {
	fn run<F: 'static + Send + Fn(usize) -> Fut, Fut: 'static + Send + Future<Output = Self>>(
	test: F,
	threads: usize,
	cfg: Config,
	) -> Self {
	crate::SendExecutor::new(cfg.scale_threads(threads)).run(
	stream::iter(0..cfg.repeat_count)
	.for_each_concurrent(cfg.max_concurrency, apply_timeout!(cfg, test)),
	)
	}
	}

	/// Configuration variables for a single test run.
	#[derive(Clone)]
	pub struct Config {
	repeat_count: usize,
	max_concurrency: usize,
	max_threads: usize,
	timeout: Option<Duration>,
	}

	fn env_var<T: std::str::FromStr>(name: &str, default: T) -> T {
	std::env::var(name).unwrap_or_default().parse().unwrap_or(default)
	}

	impl Config {
	fn get() -> Self {
	let repeat_count = std::cmp::max(1, env_var("FASYNC_TEST_REPEAT_COUNT", 1));
	let max_concurrency = env_var("FASYNC_TEST_MAX_CONCURRENCY", 0);
	let timeout_seconds = env_var("FASYNC_TEST_TIMEOUT_SECONDS", 0);
	let max_threads = env_var("FASYNC_TEST_MAX_THREADS", 0);
	let timeout =
	if timeout_seconds == 0 { None } else { Some(Duration::from_secs(timeout_seconds)) };
	Self { repeat_count, max_concurrency, max_threads, timeout }
	}

	// Scale a hard-coded thread count by some factor to account for increased concurrency in the config.
	fn scale_threads(&self, test_threads: usize) -> usize {
	// We try to scale up by the maximum concurrency we'll see.
	let scale = if self.max_concurrency == 0 {
	// If concurrency is unbounded, we'll see a maximum of the test repetitions.
	self.repeat_count
	} else {
	// Otherwise the maximum concurrency will be the lower of repeat count and the concurrency cap.
	std::cmp::min(self.repeat_count, self.max_concurrency)
	};
	// Without resource constraints, we'd like to run with our test threads scaled up by the cooncurrency.
	let desired_threads = test_threads * scale;
	// Account for resource constraints
	let capped_threads = if self.max_threads == 0 {
	desired_threads
	} else {
	std::cmp::min(desired_threads, self.max_threads)
	};
	// Always run AT LEAST the typed in number of threads in the test definition.
	std::cmp::max(capped_threads, test_threads)
	}

	fn in_parallel(&self, f: Arc<dyn 'static + Send + Sync + Fn()>) {
	// N-1 background threads...
	let threads: Vec<_> = std::iter::repeat_with(\|\| {
	let f = f.clone();
	std::thread::spawn(move \|\| f())
	})
	.take(self.scale_threads(1) - 1)
	.collect();
	// ... and we'll consume this thread to get to N.
	f();
	threads.into_iter().for_each(\|t\| t.join().expect("worker threads should be joinable"));
	}
	}

	/// Runs a test in an executor, potentially repeatedly and concurrently
	pub fn run_singlethreaded_test<F, Fut, R>(test: F) -> R
	where
	F: 'static + Send + Sync + Fn(usize) -> Fut,
	Fut: 'static + Future<Output = R>,
	R: TestResult,
	{
	TestResult::run_singlethreaded(Arc::new(move \|run\| test(run).boxed_local()), Config::get())
	}

	/// Runs a test in an executor until it's stalled
	#[cfg(target_os = "fuchsia")]
	pub fn run_until_stalled_test<F, Fut, R>(executor: &mut crate::TestExecutor, test: F) -> R
	where
	F: 'static + Fn(usize) -> Fut,
	Fut: 'static + Future<Output = R>,
	R: TestResult,
	{
	match TestResult::run_until_stalled(executor, test, Config::get()) {
	Poll::Ready(result) => result,
	_ => panic!(
	"Stalled without completing. Consider using \"run_singlethreaded\", or check for a deadlock."
	),
	}
	}

	/// Runs a test in an executor, potentially repeatedly and concurrently
	pub fn run_test<F, Fut, R>(test: F, threads: usize) -> R
	where
	F: 'static + Send + Fn(usize) -> Fut,
	Fut: 'static + Send + Future<Output = R>,
	R: MultithreadedTestResult,
	{
	MultithreadedTestResult::run(test, threads, Config::get())
	}

	#[cfg(test)]
	mod tests {
	use super::{Config, MultithreadedTestResult, TestResult};
	use futures::lock::Mutex;
	use futures::prelude::*;
	use std::collections::HashSet;
	use std::sync::Arc;
	use std::time::Duration;

	#[test]
	fn scale_threads() {
	let cfg = \|repeat_count, max_concurrency, max_threads\| Config {
	repeat_count,
	max_concurrency,
	max_threads,
	timeout: None,
	};
	// Unbounded work should look like tests_per_thread * repeat_count
	assert_eq!(cfg(1, 0, 0).scale_threads(1), 1);
	assert_eq!(cfg(1, 0, 0).scale_threads(20), 20);
	assert_eq!(cfg(30, 0, 0).scale_threads(1), 30);
	assert_eq!(cfg(30, 0, 0).scale_threads(20), 600);
	// Max concurrency should affect repetition count
	assert_eq!(cfg(30, 1, 0).scale_threads(20), 20);
	// Capping thread count should not decrease programmatic maximum
	assert_eq!(cfg(1, 0, 5).scale_threads(10), 10);
	assert_eq!(cfg(1, 0, 15).scale_threads(10), 10);
	}

	#[test]
	fn run_singlethreaded() {
	const REPEAT_COUNT: usize = 1000;
	const MAX_THREADS: usize = 10;
	let pending_runs: Arc<Mutex<HashSet<_>>> =
	Arc::new(Mutex::new((0..REPEAT_COUNT).collect()));
	let pending_runs_child = pending_runs.clone();
	TestResult::run_singlethreaded(
	Arc::new(move \|i\| {
	let pending_runs_child = pending_runs_child.clone();
	async move {
	assert!(pending_runs_child.lock().await.remove(&i));
	}
	.boxed_local()
	}),
	Config {
	repeat_count: REPEAT_COUNT,
	max_concurrency: 0,
	max_threads: MAX_THREADS,
	timeout: None,
	},
	);
	assert!(pending_runs.try_lock().unwrap().is_empty());
	}

	// TODO(https://fxbug.dev/42138715): should_panic tests trigger LSAN
	#[ignore]
	#[test]
	#[should_panic]
	fn run_singlethreaded_with_timeout() {
	TestResult::run_singlethreaded(
	Arc::new(move \|_\| {
	async move {
	futures::future::pending::<()>().await;
	}
	.boxed_local()
	}),
	Config {
	repeat_count: 1,
	max_concurrency: 0,
	max_threads: 0,
	timeout: Some(Duration::from_millis(1)),
	},
	);
	}

	#[test]
	#[cfg(target_os = "fuchsia")]
	fn run_until_stalled() {
	const REPEAT_COUNT: usize = 1000;
	let pending_runs: Arc<Mutex<HashSet<_>>> =
	Arc::new(Mutex::new((0..REPEAT_COUNT).collect()));
	let pending_runs_child = pending_runs.clone();
	match TestResult::run_until_stalled(
	&mut crate::TestExecutor::new(),
	move \|i\| {
	let pending_runs_child = pending_runs_child.clone();
	async move {
	assert!(pending_runs_child.lock().await.remove(&i));
	}
	},
	Config {
	repeat_count: REPEAT_COUNT,
	max_concurrency: 1,
	max_threads: 1,
	timeout: None,
	},
	) {
	std::task::Poll::Ready(()) => (),
	_ => panic!("Expected everything stalled"),
	}
	assert!(pending_runs.try_lock().unwrap().is_empty());
	}

	#[test]
	fn run() {
	const REPEAT_COUNT: usize = 1000;
	const THREADS: usize = 4;
	let pending_runs: Arc<Mutex<HashSet<_>>> =
	Arc::new(Mutex::new((0..REPEAT_COUNT).collect()));
	let pending_runs_child = pending_runs.clone();
	MultithreadedTestResult::run(
	move \|i\| {
	let pending_runs_child = pending_runs_child.clone();
	async move {
	assert!(pending_runs_child.lock().await.remove(&i));
	}
	},
	THREADS,
	Config {
	repeat_count: REPEAT_COUNT,
	max_concurrency: 0,
	max_threads: THREADS,
	timeout: None,
	},
	);
	assert!(pending_runs.try_lock().unwrap().is_empty());
	}

	// TODO(https://fxbug.dev/42138715): should_panic tests trigger LSAN
	#[ignore]
	#[test]
	#[should_panic]
	fn run_with_timeout() {
	const THREADS: usize = 4;
	MultithreadedTestResult::run(
	move \|_\| async move {
	futures::future::pending::<()>().await;
	},
	THREADS,
	Config {
	repeat_count: 1,
	max_concurrency: 0,
	max_threads: 0,
	timeout: Some(Duration::from_millis(1)),
	},
	);
	}
	}