1 files changed, 56 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/iter_nth.rs b/src/tools/clippy/tests/ui/iter_nth.rs
new file mode 100644
index 000000000..9c21dd82e
--- /dev/null
+++ b/src/tools/clippy/tests/ui/iter_nth.rs
@@ -0,0 +1,56 @@
+// aux-build:option_helpers.rs
+
+#![warn(clippy::iter_nth)]
+
+#[macro_use]
+extern crate option_helpers;
+
+use option_helpers::IteratorFalsePositives;
+use std::collections::VecDeque;
+
+/// Struct to generate false positives for things with `.iter()`.
+#[derive(Copy, Clone)]
+struct HasIter;
+
+impl HasIter {
+    fn iter(self) -> IteratorFalsePositives {
+        IteratorFalsePositives { foo: 0 }
+    }
+
+    fn iter_mut(self) -> IteratorFalsePositives {
+        IteratorFalsePositives { foo: 0 }
+    }
+}
+
+/// Checks implementation of `ITER_NTH` lint.
+fn iter_nth() {
+    let mut some_vec = vec![0, 1, 2, 3];
+    let mut boxed_slice: Box<[u8]> = Box::new([0, 1, 2, 3]);
+    let mut some_vec_deque: VecDeque<_> = some_vec.iter().cloned().collect();
+
+    {
+        // Make sure we lint `.iter()` for relevant types.
+        let bad_vec = some_vec.iter().nth(3);
+        let bad_slice = &some_vec[..].iter().nth(3);
+        let bad_boxed_slice = boxed_slice.iter().nth(3);
+        let bad_vec_deque = some_vec_deque.iter().nth(3);
+    }
+
+    {
+        // Make sure we lint `.iter_mut()` for relevant types.
+        let bad_vec = some_vec.iter_mut().nth(3);
+    }
+    {
+        let bad_slice = &some_vec[..].iter_mut().nth(3);
+    }
+    {
+        let bad_vec_deque = some_vec_deque.iter_mut().nth(3);
+    }
+
+    // Make sure we don't lint for non-relevant types.
+    let false_positive = HasIter;
+    let ok = false_positive.iter().nth(3);
+    let ok_mut = false_positive.iter_mut().nth(3);
+}
+
+fn main() {}