Writing Automated Tests

Testing validates that code behaves as intended. Rust’s type system catches many bugs at compile time, but cannot verify business logic correctness. Automated tests ensure your code produces expected outputs for given inputs.

Rust provides built-in testing framework with attributes, macros, and execution control. This chapter covers test organization, writing effective tests, and test execution strategies.

Test Structure

Tests in Rust follow a standard pattern:

• Setup: Arrange necessary data or state
• Exercise: Execute the code under test
• Assert: Verify results match expectations

The #[test] attribute marks functions as tests, and cargo test runs all tests in parallel by default.