(tests) Test unused file level directives are flagged

Author: maxmynter

crates/ruff_linter/resources/test/fixtures/ruff/RUF100_6.py

@@ -0,0 +1 @@
+# ruff: noqa: F841 -- intentional unused file directive; will be removed

crates/ruff_linter/src/rules/ruff/mod.rs

@@ -314,6 +314,16 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn ruff_noqa_filedirective_unused() -> Result<()> {
+        let diagnostics = test_path(
+            Path::new("ruff/RUF100_6.py"),
+            &settings::LinterSettings::for_rules(vec![Rule::UnusedNOQA]),
+        )?;
+        assert_messages!(diagnostics);
+        Ok(())
+    }
+
     #[test]
     fn ruff_per_file_ignores() -> Result<()> {
         let diagnostics = test_path(

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__ruff_noqa_filedirective_unused.snap

@@ -0,0 +1,13 @@
+---
+source: crates/ruff_linter/src/rules/ruff/mod.rs
+---
+RUF100_6.py:1:1: RUF100 [*] Unused `noqa` directive (non-enabled: `F841`)
+  |
+1 | # ruff: noqa: F841 -- intentional unused file directive; will be removed
+  | ^^^^^^^^^^^^^^^^^^ RUF100
+  |
+  = help: Remove unused `noqa` directive
+
+ℹ Safe fix
+1   |-# ruff: noqa: F841 -- intentional unused file directive; will be removed
+  1 |+