additional specializations tests

library/alloc/tests/vec.rs

@@ -785,6 +785,28 @@ fn test_from_iter_specialization() {
     assert_eq!(srcptr, sinkptr);
 }
 
+#[test]
+fn test_from_iter_partially_drained_in_place_specialization() {
+    let src: Vec<usize> = vec![0usize; 10];
+    let srcptr = src.as_ptr();
+    let mut iter = src.into_iter();
+    iter.next();
+    iter.next();
+    let sink = iter.collect::<Vec<_>>();
+    let sinkptr = sink.as_ptr();
+    assert_eq!(srcptr, sinkptr);
+}
+
+#[test]
+fn test_extend_in_place_specialization() {
+    let src: Vec<usize> = vec![0usize; 1];
+    let srcptr = src.as_ptr();
+    let mut dst = Vec::new();
+    dst.extend(src.into_iter());
+    let dstptr = dst.as_ptr();
+    assert_eq!(srcptr, dstptr);
+}
+
 #[test]
 fn test_from_iter_specialization_with_iterator_adapters() {
     fn assert_in_place_trait<T: InPlaceIterable>(_: &T) {};