tanu

High-performance, async-friendly and ergonomic WebAPI testing framework for Rust

Motivation

As a long time backend engineer, I have always been passionate about building reliable and efficient systems. When working with WebAPIs, ensuring correctness, stability, and performance is crucial, yet I often found existing testing frameworks lacking in speed, flexibility, or Rust-native support. This led me to create a WebAPI testing framework in Rust.

While some WebAPI testing tools exist for Rust, they often lack ergonomics, are too low-level, or don't integrate well with modern Rust web frameworks. My goal was to create a framework that is:

• Fast and lightweight – Leveraging Rust’s zero-cost abstractions to minimize unnecessary overhead.
• Type-safe and ergonomic – Taking advantage of Rust’s strong type system to prevent common errors at compile time.
• Easily extensible – Allowing developers to integrate custom assertions, mocking, and performance metrics seamlessly.
• Concurrency and async-friendly – Supporting asynchronous requests and concurrent execution to test APIs efficiently.

I tried multiple solutions in the past but encountered significant limitations:

• Postman - Postman is a great tool but not designed for API end-to-end testing. You need a GUI and have to write assertions in JavaScript, which results in massive JSON files that become difficult to manage.
• Playwright - Playwright is an excellent framework for web end-to-end testing. While it does support API testing, I wanted to use the same language for both API implementation and tests, which Playwright does not offer.
• Rust Standard Test Framework - I attempted multiple times to write API tests using #[test], along with tokio, test-case, and reqwest crates. While functional, this approach lacked structure and ergonomics for writing effective tests at scale. I wanted a dedicated framework to simplify and streamline the process.

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