24.2 Kinds of Tests

Rust categorizes tests into three main types:

  1. Unit Tests

    • Validate small, focused pieces of functionality within the same file or module.
    • Can access private items, enabling thorough testing of internal helpers.

  2. Integration Tests

    • Stored in the tests/ directory, with each file acting as a separate crate.
    • Import your library as a dependency to test only the public API.

  3. Documentation Tests

    • Embedded in code examples within documentation comments (/// or //!).
    • Verify that the documentation’s code examples compile and run correctly.

By default, running cargo test compiles and executes all three categories of tests.