Add test for MaybeUninit::array_assume_init

Author: joboet

library/core/tests/lib.rs

@@ -36,6 +36,8 @@
 #![feature(raw)]
 #![feature(sort_internals)]
 #![feature(slice_partition_at_index)]
+#![feature(maybe_uninit_uninit_array)]
+#![feature(maybe_uninit_array_assume_init)]
 #![feature(maybe_uninit_extra)]
 #![feature(maybe_uninit_write_slice)]
 #![feature(min_specialization)]

library/core/tests/mem.rs

@@ -140,6 +140,22 @@ fn assume_init_good() {
     assert!(TRUE);
 }
 
+#[test]
+fn uninit_array_assume_init() {
+    let mut array: [MaybeUninit<i16>; 5] = MaybeUninit::uninit_array();
+    array[0].write(3);
+    array[1].write(1);
+    array[2].write(4);
+    array[3].write(1);
+    array[4].write(5);
+
+    let array = unsafe {
+        MaybeUninit::array_assume_init(array)
+    };
+    
+    assert_eq!(array, [3, 1, 4, 1, 5]);
+}
+
 #[test]
 fn uninit_write_slice() {
     let mut dst = [MaybeUninit::new(255); 64];