items_after_test_module disagrees with widespread practice

[dtolnay]

Summary

mod bar;
mod foo;

#[cfg(test)]
mod tests;

use bar::Trait;

pub fn fun() {}

I believe clippy should not dislike this code. Declaring modules at the top of the file is extremely common practice. People disagree on whether mod goes before or after use, but both of those ways are way more common than putting mod last in a file.

Lint Name

items_after_test_module

Reproducer

// src/lib.rs

#[cfg(test)]
mod tests;

pub fn f() {}

// src/tests.rs (empty)

$ cargo clippy --tests

warning: items were found after the testing module
 --> src/lib.rs:2:1
  |
2 | / mod tests;
3 | |
4 | | pub fn f() {}
  | |_____________^
  |
  = help: move the items to before the testing module was defined
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#items_after_test_module
  = note: `#[warn(clippy::items_after_test_module)]` on by default

Version

rustc 1.71.0-nightly (f5559e338 2023-04-24)
binary: rustc
commit-hash: f5559e338256f17ada6d82b429acc2dbd8facc9c
commit-date: 2023-04-24
host: x86_64-unknown-linux-gnu
release: 1.71.0-nightly
LLVM version: 16.0.2

Additional Labels

No response

[dtolnay]

@blyxyas @dswij (#10578)

[blyxyas]

I think downgrading here isn't the correct move. But instead ignore module imports.

The lint was never intended to catch

#[cfg(test)]
mod tests;

It was intended to catch modules with a body.

#[cfg(test)]
mod tests {
// [•••]
}

So this isn't the lint level's fault, this is just a bug.

[blyxyas]

@rustbot claim

[ilyagr]

I'm still having problems. I'm not sure if it's a bug in clippy or in the test-case library. I filed frondeus/test-case#122.