diff --git a/CHANGELOG.md b/CHANGELOG.md
index 47a503510c10..ab3033ae4e33 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4964,6 +4964,7 @@ Released 2018-09-13
[`unchecked_duration_subtraction`]: https://rust-lang.github.io/rust-clippy/master/index.html#unchecked_duration_subtraction
[`undocumented_unsafe_blocks`]: https://rust-lang.github.io/rust-clippy/master/index.html#undocumented_unsafe_blocks
[`undropped_manually_drops`]: https://rust-lang.github.io/rust-clippy/master/index.html#undropped_manually_drops
+[`unflagged_test_modules`]: https://rust-lang.github.io/rust-clippy/master/index.html#unflagged_test_modules
[`unicode_not_nfc`]: https://rust-lang.github.io/rust-clippy/master/index.html#unicode_not_nfc
[`unimplemented`]: https://rust-lang.github.io/rust-clippy/master/index.html#unimplemented
[`uninit_assumed_init`]: https://rust-lang.github.io/rust-clippy/master/index.html#uninit_assumed_init
diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs
index 2331e857b1f7..f048b3551fae 100644
--- a/clippy_lints/src/declared_lints.rs
+++ b/clippy_lints/src/declared_lints.rs
@@ -606,6 +606,7 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
crate::types::VEC_BOX_INFO,
crate::undocumented_unsafe_blocks::UNDOCUMENTED_UNSAFE_BLOCKS_INFO,
crate::undocumented_unsafe_blocks::UNNECESSARY_SAFETY_COMMENT_INFO,
+ crate::unflagged_test_modules::UNFLAGGED_TEST_MODULES_INFO,
crate::unicode::INVISIBLE_CHARACTERS_INFO,
crate::unicode::NON_ASCII_LITERAL_INFO,
crate::unicode::UNICODE_NOT_NFC_INFO,
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 100cba456793..2dbc40e67bc9 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -295,6 +295,7 @@ mod trait_bounds;
mod transmute;
mod types;
mod undocumented_unsafe_blocks;
+mod unflagged_test_modules;
mod unicode;
mod uninit_vec;
mod unit_return_expecting_ord;
@@ -938,6 +939,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|_| Box::new(let_with_type_underscore::UnderscoreTyped));
store.register_late_pass(|_| Box::new(allow_attributes::AllowAttribute));
store.register_late_pass(move |_| Box::new(manual_main_separator_str::ManualMainSeparatorStr::new(msrv())));
+ store.register_late_pass(|_| Box::new(unflagged_test_modules::UnflaggedTestModules));
// add lints here, do not remove this comment, it's used in `new_lint`
}
diff --git a/clippy_lints/src/unflagged_test_modules.rs b/clippy_lints/src/unflagged_test_modules.rs
new file mode 100644
index 000000000000..658d92b04b4a
--- /dev/null
+++ b/clippy_lints/src/unflagged_test_modules.rs
@@ -0,0 +1,73 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use rustc_hir::*;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::{symbol::sym, BytePos};
+
+declare_clippy_lint! {
+ /// ### What it does
+ ///
+ /// Triggers when a testing module (that contains "test" or "tests" in its name) isn't flagged with the `#[cfg(test)]` attribute.
+ ///
+ /// ### Why is this bad?
+ ///
+ /// The attribute `#[cfg(test)]` is used to tell Rust to compile and run the test code only when you run `cargo test` and not when you run `cargo build`. This saves compile time and space in the resulting compiled artifact because tests are not included. So not using `#[cfg(test)]` for tests is both a waste of time and space.
+ ///
+ /// ### Example
+ /// ```rust
+ /// mod my_cool_tests {
+ /// // [...]
+ /// }
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// #[cfg(test)]
+ /// mod my_cool_tests {
+ /// // [...]
+ /// }
+ /// ```
+ #[clippy::version = "1.70.0"]
+ pub UNFLAGGED_TEST_MODULES,
+ pedantic,
+ "the testing module `my_cool_tests` wasn't marked with `#[cfg(test)]`"
+}
+declare_lint_pass!(UnflaggedTestModules => [UNFLAGGED_TEST_MODULES]);
+
+impl LateLintPass<'_> for UnflaggedTestModules {
+ fn check_item_post(&mut self, cx: &LateContext<'_>, item: &rustc_hir::Item<'_>) {
+ if let ItemKind::Mod(_) = item.kind {
+ // If module name contains *test* or *tests*.
+ if item
+ .ident
+ .name
+ .to_ident_string()
+ .split('_')
+ .any(|seg| seg == "test" || seg == "tests")
+ {
+ for attr in cx.tcx.get_attrs(item.owner_id.to_def_id(), sym::cfg) {
+ if_chain! {
+ if attr.has_name(sym::cfg);
+ if let Some(items) = attr.meta_item_list();
+ if let [item] = &*items;
+ if item.has_name(sym::test);
+ then {
+ return;
+ }
+ }
+ }
+ // If no #[cfg(test)] is found
+ span_lint_and_sugg(
+ cx,
+ UNFLAGGED_TEST_MODULES,
+ item.ident.span.with_lo(
+ item.ident.span.lo() - BytePos(4), // Add `mod` keyword
+ ),
+ "this testing module isn't flagged with #[cfg(test)]",
+ "add the attribute",
+ format!("#[cfg(test)]\nmod {}", item.ident.as_str()),
+ rustc_errors::Applicability::MachineApplicable,
+ );
+ }
+ }
+ }
+}
diff --git a/tests/ui/unflagged_test_modules.fixed b/tests/ui/unflagged_test_modules.fixed
new file mode 100644
index 000000000000..427202338876
--- /dev/null
+++ b/tests/ui/unflagged_test_modules.fixed
@@ -0,0 +1,18 @@
+// run-rustfix
+// compile-flags: --test
+#![allow(unused)]
+#![warn(clippy::unflagged_test_modules)]
+
+fn main() {
+ // test code goes here
+}
+
+#[cfg(test)]
+mod tests {
+ fn my_test() {}
+}
+
+#[cfg(test)]
+mod test {
+ fn my_other_test() {}
+}
diff --git a/tests/ui/unflagged_test_modules.rs b/tests/ui/unflagged_test_modules.rs
new file mode 100644
index 000000000000..602ec95057b8
--- /dev/null
+++ b/tests/ui/unflagged_test_modules.rs
@@ -0,0 +1,17 @@
+// run-rustfix
+// compile-flags: --test
+#![allow(unused)]
+#![warn(clippy::unflagged_test_modules)]
+
+fn main() {
+ // test code goes here
+}
+
+#[cfg(test)]
+mod tests {
+ fn my_test() {}
+}
+
+mod test {
+ fn my_other_test() {}
+}
diff --git a/tests/ui/unflagged_test_modules.stderr b/tests/ui/unflagged_test_modules.stderr
new file mode 100644
index 000000000000..3dfc408f167c
--- /dev/null
+++ b/tests/ui/unflagged_test_modules.stderr
@@ -0,0 +1,15 @@
+error: this testing module isn't flagged with #[cfg(test)]
+ --> $DIR/unflagged_test_modules.rs:15:1
+ |
+LL | mod test {
+ | ^^^^^^^^
+ |
+ = note: `-D clippy::unflagged-test-modules` implied by `-D warnings`
+help: add the attribute
+ |
+LL + #[cfg(test)]
+LL ~ mod test {
+ |
+
+error: aborting due to previous error
+