1 files changed, 32 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/suspicious_map.rs b/src/tools/clippy/tests/ui/suspicious_map.rs
new file mode 100644
index 000000000..3a2a10cf0
--- /dev/null
+++ b/src/tools/clippy/tests/ui/suspicious_map.rs
@@ -0,0 +1,32 @@
+#![warn(clippy::suspicious_map)]
+
+fn main() {
+    let _ = (0..3).map(|x| x + 2).count();
+
+    let f = |x| x + 1;
+    let _ = (0..3).map(f).count();
+}
+
+fn negative() {
+    // closure with side effects
+    let mut sum = 0;
+    let _ = (0..3).map(|x| sum += x).count();
+
+    // closure variable with side effects
+    let ext_closure = |x| sum += x;
+    let _ = (0..3).map(ext_closure).count();
+
+    // closure that returns unit
+    let _ = (0..3)
+        .map(|x| {
+            // do nothing
+        })
+        .count();
+
+    // external function
+    let _ = (0..3).map(do_something).count();
+}
+
+fn do_something<T>(t: T) -> String {
+    unimplemented!()
+}