web-concurrency-tester-rs 🦀🕸️

web-concurrency-tester-rs is a deterministic concurrency testing tool for Web/JavaScript environments, written entirely in Rust.

It helps developers find hard-to-reproduce race conditions in DOM operations by using advanced scheduling algorithms like Shuttle-style scheduling, DPOR (Dynamic Partial Order Reduction), and PCT (Probabilistic Concurrency Testing).

✨ Features

• Deterministic Execution: Controls the order of async operations and events to reliably reproduce bugs.
• Advanced Race Detection:
  • FastTrack / Vector Clocks: Efficiently tracks happens-before relationships.
  • DPOR: Prunes the search space to test only meaningful interleavings.
  • PCT: Mathematically guaranteed bug detection probabilities for depth-bounded races.
• Embedded JS Engine: Powered by boa_engine and oxc_parser for direct analysis and execution in Rust.

📦 Installation

You can install the tool directly from crates.io:

cargo install web-concurrency-tester-rs

🚀 Usage

1. Create a Test Case

Create an HTML file (e.g., test.html) containing the JavaScript logic you want to verify.

<button onclick="inc()">Increment</button>
<script>
  let count = 0;

  // A function with a potential race condition
  async function inc() {
    let temp = count;
    // Context switch point
    await new Promise((r) => setTimeout(r, 10));
    count = temp + 1;
  }
</script>

2. Run the Test

If you installed via cargo:

web-concurrency-tester-rs test.html

Or if you are running from the source code:

cargo run --release -- test.html

Output Example

The tool explores multiple execution schedules and reports any detected races:

  DETECTED RACES:
  [Write-Write] 'count': Task 0 vs Task 1
  ...

📄 License

This project is licensed under the Mozilla Public License 2.0 (MPL-2.0). See the LICENSE file for details.