Testing
Rust is the dominant language for production WebAssembly. The Rust/Wasm toolchain — wasm-pack, wasm-bindgen, and web-sys — is mature and well-documented. But testing Rust Wasm projects requires thinking at multiple levels simultaneously: Rust logic, Wasm compilation, JavaScript integration, and browser behavior. This guide covers the complete testing
Testing
Rust compiled to WebAssembly introduces a new class of testing challenge: your code runs in a browser or Node.js context, not on the OS. Standard cargo test doesn't run wasm tests. wasm-pack test does. This guide covers how to write testable Rust wasm code, use wasm-
Testing
Testing async Rust code with #[tokio::test] handles the basics — but complex async patterns (state machines, channels, time-dependent logic, concurrent operations) need more. This guide covers advanced async testing patterns beyond the basics. The Foundation: #[tokio::test] The baseline for async Rust tests: [dev-dependencies] tokio = { version = "1&
Testing
Rust has three places to write tests: inline in the source file, in a tests/ directory for integration tests, and in doctests. Most guides cover these in isolation. This guide covers how to organize them as your project grows — shared utilities, feature-gated tests, test fixtures, and keeping test code
Rust
Code coverage tells you which lines your tests exercise. It won't tell you if your tests are good, but it does tell you what you're definitely not testing. In Rust, you have two main options: cargo-tarpaulin and cargo-llvm-cov. This guide covers both, when
Testing
Rust's error handling is excellent but undertested. Most Rust codebases test the happy path thoroughly and treat error paths as "it compiles, must be right." But error handling bugs — wrong error type returned, missing context in error messages, error chains that lose important information — cause real
Rust
```tldr Rust's embedded ecosystem has first-class testing support: defmt-test runs tests directly on-target with RTT output, QEMU lets you run ARM Cortex-M tests on a developer machine, and embedded-hal-mock lets you unit test peripheral drivers without hardware at all. Most embedded Rust
Testing
Rust CLI applications have a unique testing challenge: you can unit test the business logic, but testing the actual binary — argument parsing, output formatting, exit codes — requires running the compiled program. assert_cmd is the standard crate for this. This guide covers end-to-end CLI testing with assert_cmd
Rust
cargo test is deceptively simple on the surface. You type it, tests run. But there's a rich set of options that most Rust developers never fully explore — options that can make your test suite faster, more precise, and easier to debug. This is a deep dive into cargo
Testing
Tauri is a framework for building lightweight desktop apps with a Rust backend and a web frontend.
Rust
Testing async Rust code requires an async runtime. Tokio provides the #[tokio::test] attribute macro that wraps your test in an async executor.
Testing
cargo-nextest runs Rust tests faster and with better output than cargo test. Beyond the basics, it has a configuration system that lets you filter which tests run, partition tests across parallel CI jobs, retry flaky tests automatically, and produce JUnit XML for CI dashboards — all without changing test code.