Fix items_after_test_module for non root modules, add applicable suggestion

tests/ui/items_after_test_module/after_proc_macros.rs

@@ -0,0 +1,11 @@
+//@aux-build:../auxiliary/proc_macros.rs
+extern crate proc_macros;
+
+proc_macros::with_span! {
+    span
+    #[cfg(test)]
+    mod tests {}
+}
+
+#[test]
+fn f() {}

tests/ui/items_after_test_module/auxiliary/submodule.rs

@@ -0,0 +1,4 @@
+#[cfg(test)]
+mod tests {}
+
+fn in_submodule() {}

tests/ui/items_after_test_module/block_module.stderr

@@ -1,2 +0,0 @@
-error: Option 'test' given more than once
-

tests/ui/items_after_test_module/in_submodule.rs

@@ -0,0 +1,8 @@
+#[path = "auxiliary/submodule.rs"]
+mod submodule;
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn t() {}
+}

tests/ui/items_after_test_module/in_submodule.stderr

@@ -0,0 +1,14 @@
+error: items after a test module
+  --> $DIR/auxiliary/submodule.rs:2:1
+   |
+LL | mod tests {}
+   | ^^^^^^^^^
+LL |
+LL | fn in_submodule() {}
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::items-after-test-module` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::items_after_test_module)]`
+
+error: aborting due to previous error
+

tests/ui/items_after_test_module/multiple_modules.rs

@@ -0,0 +1,11 @@
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn f() {}
+}
+
+#[cfg(test)]
+mod more_tests {
+    #[test]
+    fn g() {}
+}

tests/ui/items_after_test_module/root_module.fixed

@@ -1,4 +1,3 @@
-//@compile-flags: --test
 #![allow(unused)]
 #![warn(clippy::items_after_test_module)]
 
@@ -6,6 +5,13 @@ fn main() {}
 
 fn should_not_lint() {}
 
+fn should_lint() {}
+
+const SHOULD_ALSO_LINT: usize = 1;
+macro_rules! should_lint {
+    () => {};
+}
+
 #[allow(dead_code)]
 #[allow(unused)] // Some attributes to check that span replacement is good enough
 #[allow(clippy::allow_attributes)]
@@ -14,10 +20,3 @@ mod tests {
     #[test]
     fn hi() {}
 }
-
-fn should_lint() {}
-
-const SHOULD_ALSO_LINT: usize = 1;
-macro_rules! should_not_lint {
-    () => {};
-}

tests/ui/items_after_test_module/root_module.rs

@@ -0,0 +1,22 @@
+#![allow(unused)]
+#![warn(clippy::items_after_test_module)]
+
+fn main() {}
+
+fn should_not_lint() {}
+
+#[allow(dead_code)]
+#[allow(unused)] // Some attributes to check that span replacement is good enough
+#[allow(clippy::allow_attributes)]
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn hi() {}
+}
+
+fn should_lint() {}
+
+const SHOULD_ALSO_LINT: usize = 1;
+macro_rules! should_lint {
+    () => {};
+}

tests/ui/items_after_test_module/root_module.stderr

@@ -0,0 +1,20 @@
+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 previous error
+