1 files changed, 51 insertions, 0 deletions
diff --git a/syn/tests/test_iterators.rs b/syn/tests/test_iterators.rs
new file mode 100644
index 0000000..f107297
--- /dev/null
+++ b/syn/tests/test_iterators.rs
@@ -0,0 +1,51 @@
+use syn::punctuated::{Pair, Punctuated};
+use syn::Token;
+
+mod features;
+
+#[macro_use]
+mod macros;
+
+macro_rules! check_exact_size_iterator {
+    ($iter:expr) => {{
+        let iter = $iter;
+        let size_hint = iter.size_hint();
+        let len = iter.len();
+        let count = iter.count();
+        assert_eq!(len, count);
+        assert_eq!(size_hint, (count, Some(count)));
+    }};
+}
+
+#[test]
+fn pairs() {
+    let mut p: Punctuated<_, Token![,]> = punctuated!(2, 3, 4);
+
+    check_exact_size_iterator!(p.pairs());
+    check_exact_size_iterator!(p.pairs_mut());
+    check_exact_size_iterator!(p.into_pairs());
+
+    let mut p: Punctuated<_, Token![,]> = punctuated!(2, 3, 4);
+
+    assert_eq!(p.pairs().next_back().map(Pair::into_value), Some(&4));
+    assert_eq!(
+        p.pairs_mut().next_back().map(Pair::into_value),
+        Some(&mut 4)
+    );
+    assert_eq!(p.into_pairs().next_back().map(Pair::into_value), Some(4));
+}
+
+#[test]
+fn iter() {
+    let mut p: Punctuated<_, Token![,]> = punctuated!(2, 3, 4);
+
+    check_exact_size_iterator!(p.iter());
+    check_exact_size_iterator!(p.iter_mut());
+    check_exact_size_iterator!(p.into_iter());
+
+    let mut p: Punctuated<_, Token![,]> = punctuated!(2, 3, 4);
+
+    assert_eq!(p.iter().next_back(), Some(&4));
+    assert_eq!(p.iter_mut().next_back(), Some(&mut 4));
+    assert_eq!(p.into_iter().next_back(), Some(4));
+}