# File rules

## Avoid generic Rust file names

### Rule

Do not name Rust source files `lib.rs` or `main.rs`.
Name library crate root files after the crate they define.
Name binary crate root files after the binary they define, or use a `_main.rs` suffix.
Set explicit Cargo paths and Bazel `srcs` when needed.

### Rationale

Generic root names make file search results and review context less clear.
Descriptive file names show which crate or binary owns the code.

## Keep Rust tests in separate files

### Rule

Put Rust tests in separate `*_test.rs` files.
Name each test file after the Rust source file or crate root that it tests.
Do not use generic test file names such as `lib_test.rs` or `main_test.rs`.
Do not add inline `#[cfg(test)]` modules.

### Rationale

Separate test files keep production modules focused and match the repository's Bazel test layout.