error: items after a test module
  --> $DIR/root_module.rs:12:1
   |
LL | mod tests {
   | ^^^^^^^^^
...
LL | fn should_lint() {}
   | ^^^^^^^^^^^^^^^^
LL |
LL | const SHOULD_ALSO_LINT: usize = 1;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | macro_rules! should_lint {
   | ^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `-D clippy::items-after-test-module` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(clippy::items_after_test_module)]`
   = help: move the items to before the test module was defined

error: aborting due to 1 previous error