diff --git a/tests/debug.rs b/tests/debug.rs
index 843c0acad..19f046983 100644
--- a/tests/debug.rs
+++ b/tests/debug.rs
@@ -11,8 +11,9 @@ where
 #[test]
 fn debug_binary_heap() {
     use std::collections::BinaryHeap;
-    let heap: BinaryHeap<_> = (0..10).collect();
+    let mut heap: BinaryHeap<_> = (0..10).collect();
     check(heap.par_iter());
+    check(heap.par_drain());
     check(heap.into_par_iter());
 }
 
@@ -39,14 +40,16 @@ fn debug_hash_map() {
     let mut map: HashMap<_, _> = (0..10).enumerate().collect();
     check(map.par_iter());
     check(map.par_iter_mut());
+    check(map.par_drain());
     check(map.into_par_iter());
 }
 
 #[test]
 fn debug_hash_set() {
     use std::collections::HashSet;
-    let set: HashSet<_> = (0..10).collect();
+    let mut set: HashSet<_> = (0..10).collect();
     check(set.par_iter());
+    check(set.par_drain());
     check(set.into_par_iter());
 }
 
@@ -65,6 +68,7 @@ fn debug_vec_deque() {
     let mut deque: VecDeque<_> = (0..10).collect();
     check(deque.par_iter());
     check(deque.par_iter_mut());
+    check(deque.par_drain(..));
     check(deque.into_par_iter());
 }
 
@@ -104,6 +108,12 @@ fn debug_str() {
     check(s.par_split_whitespace());
 }
 
+#[test]
+fn debug_string() {
+    let mut s = "a b c d\ne f g".to_string();
+    s.par_drain(..);
+}
+
 #[test]
 fn debug_vec() {
     let mut v: Vec<_> = (0..10).collect();
@@ -116,6 +126,7 @@ fn debug_vec() {
     check(v.par_windows(42));
     check(v.par_split(|x| x % 3 == 0));
     check(v.par_split_mut(|x| x % 3 == 0));
+    check(v.par_drain(..));
     check(v.into_par_iter());
 }