feat(skills): require descriptive Rust test names

src/skills/style/rust/rules/files.md

@@ -19,6 +19,8 @@ Descriptive file names show which crate or binary owns the code.
 ### 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