Crate test_executors 

This crate provides extremely simple, yet useful, async executors. They are primarily useful for writing unit tests without bringing in a full-blown executor such as tokio.

Quick Start

use test_executors::{spin_on, sleep_on};

// Run a simple async function
let result = spin_on(async {
    42
});
assert_eq!(result, 42);

// Run an async function that sleeps
let result = sleep_on(async {
    // Your async code here
    "Hello, async!"
});
assert_eq!(result, "Hello, async!");

Available Executors

The crate provides three main executors:

• spin_on - Polls a future in a busy loop on the current thread. Best for CPU-bound tasks or when latency is critical.
• sleep_on - Polls a future on the current thread, sleeping between polls. Best for I/O-bound tasks to avoid burning CPU.
• spawn_on - Spawns a future on a new thread, polling it there. Best for fire-and-forget tasks.

Platform Support

Native Platforms

All executors work as described above on native platforms (Linux, macOS, Windows, etc.).

WebAssembly Support

This crate has special support for wasm32 targets:

• The async_test macro automatically adapts to use wasm-bindgen-test on WASM
• spawn_local uses wasm_bindgen_futures::spawn_local on WASM targets

Features

async_test Macro

The async_test macro allows you to write async tests that work on both native and WASM targets:

use test_executors::async_test;

#[async_test]
async fn my_test() {
    let value = async { 42 }.await;
    assert_eq!(value, 42);
}

Integration with some_executor

This crate implements the some_executor trait for all executors, allowing them to be used in executor-agnostic code:

use test_executors::aruntime::SpinRuntime;
use some_executor::SomeExecutor;

let mut runtime = SpinRuntime::new();
// Use runtime with some_executor traits

Utilities

The crate also provides utility functions and types:

• poll_once and poll_once_pin - Poll a future exactly once
• spawn_local - Platform-aware spawning that works on both native and WASM

Re-exports

pub use some_executor;

Modules

aruntime

Async runtime implementations for test executors.

Functions

poll_once

Polls a pinned future exactly once and returns the result.

poll_once_pin

Polls a future exactly once after pinning it.

sleep_on

Blocks the calling thread until a future is ready, sleeping between polls.

spawn_local

Spawns a future in a platform-appropriate way without waiting for completion.

spawn_on

Spawns a future on a new thread and returns immediately without waiting for completion.

spin_on

Blocks the calling thread until a future is ready, using a spinloop.

Attribute Macros

async_test

A procedural macro that converts an async function into a test function.