1 files changed, 47 insertions, 0 deletions
diff --git a/tests/adaptors_no_collect.rs b/tests/adaptors_no_collect.rs
new file mode 100644
index 0000000..a47f906
--- /dev/null
+++ b/tests/adaptors_no_collect.rs
@@ -0,0 +1,47 @@
+use itertools::Itertools;
+
+struct PanickingCounter {
+    curr: usize,
+    max: usize,
+}
+
+impl Iterator for PanickingCounter {
+    type Item = ();
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.curr += 1;
+
+        if self.curr == self.max {
+            panic!(
+                "Input iterator reached maximum of {} suggesting collection by adaptor",
+                self.max
+            );
+        }
+
+        Some(())
+    }
+}
+
+fn no_collect_test<A, T>(to_adaptor: T)
+    where A: Iterator, T: Fn(PanickingCounter) -> A
+{
+    let counter = PanickingCounter { curr: 0, max: 10_000 };
+    let adaptor = to_adaptor(counter);
+
+    for _ in adaptor.take(5) {}
+}
+
+#[test]
+fn permutations_no_collect() {
+    no_collect_test(|iter| iter.permutations(5))
+}
+
+#[test]
+fn combinations_no_collect() {
+    no_collect_test(|iter| iter.combinations(5))
+}
+
+#[test]
+fn combinations_with_replacement_no_collect() {
+    no_collect_test(|iter| iter.combinations_with_replacement(5))
+}
+\ No newline at end of file