Clippy lint · Restriction · checked with Clippy 0.1.99

clippy::tests_outside_test_module: Triggers when a testing function (marked with the #[test] attribute) isn’t inside a testing module (marked with #[cfg(test)])

What it meansTriggers when a testing function (marked with the #[test] attribute) isn’t inside a testing module (marked with #[cfg(test)]). It is in the restriction group and off by default.

Does it matter?

The idiomatic (and more performant) way of writing tests is inside a testing module (flagged with #[cfg(test)]), having test functions outside of this module is confusing and may lead to them being “hidden”.

Lints that forbid language features for specific codebases (no unwrap, no indexing...). Off by default; pick them one by one, never the whole group.

How to fix it

Clippy does not fix this one automatically. Change the code by hand:

Flagged

#[test]
fn my_cool_test() {
    // [...]
}

#[cfg(test)]
mod tests {
    // [...]
}

Write this instead

#[cfg(test)]
mod tests {
    #[test]
    fn my_cool_test() {
        // [...]
    }
}

Turn it off, or on

It is off by default. To use it, set it to warn or deny:

Whole crate (Cargo.toml)

[lints.clippy]
tests_outside_test_module = "warn"

In code

#![warn(clippy::tests_outside_test_module)]

One run

cargo clippy -- -W clippy::tests-outside-test-module

The [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.

Restrictiongroup

allowdefault level

nofixed by cargo clippy --fix

1.70.0added in Rust

Clippy's own documentation

What it does

Triggers when a testing function (marked with the #[test] attribute) isn’t inside a testing module (marked with #[cfg(test)]).

Why restrict this?

The idiomatic (and more performant) way of writing tests is inside a testing module (flagged with #[cfg(test)]), having test functions outside of this module is confusing and may lead to them being “hidden”.

Example

#[test]
fn my_cool_test() {
    // [...]
}

#[cfg(test)]
mod tests {
    // [...]
}

Use instead:

#[cfg(test)]
mod tests {
    #[test]
    fn my_cool_test() {
        // [...]
    }
}

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

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