1 files changed, 20 insertions, 0 deletions
diff --git a/tests/ui/lint/lint_map_unit_fn.rs b/tests/ui/lint/lint_map_unit_fn.rs
new file mode 100644
index 000000000..dc1ecbf84
--- /dev/null
+++ b/tests/ui/lint/lint_map_unit_fn.rs
@@ -0,0 +1,20 @@
+#![deny(map_unit_fn)]
+
+fn foo(items: &mut Vec<u8>) {
+    items.sort();
+}
+
+fn main() {
+    let mut x: Vec<Vec<u8>> = vec![vec![0, 2, 1], vec![5, 4, 3]];
+    x.iter_mut().map(foo);
+    //~^ ERROR `Iterator::map` call that discard the iterator's values
+    x.iter_mut().map(|items| {
+    //~^ ERROR `Iterator::map` call that discard the iterator's values
+        items.sort();
+    });
+    let f = |items: &mut Vec<u8>| {
+        items.sort();
+    };
+    x.iter_mut().map(f);
+    //~^ ERROR `Iterator::map` call that discard the iterator's values
+}