add tests

Author: Qelxiros

library/coretests/tests/lib.rs

@@ -77,6 +77,7 @@
 #![feature(never_type)]
 #![feature(next_index)]
 #![feature(numfmt)]
+#![feature(option_reduce)]
 #![feature(pattern)]
 #![feature(pointer_is_aligned_to)]
 #![feature(portable_simd)]

library/coretests/tests/option.rs

@@ -584,3 +584,15 @@ fn as_slice() {
     assert_eq!(A, &[44]);
     assert_eq!(B, &[]);
 }
+
+#[test]
+fn reduce_options() {
+    let x = Some(10);
+    let y = Some(7);
+    let z = None::<i32>;
+
+    assert_eq!(x.reduce(y, |x, y| x + y), Some(17));
+    assert_eq!(x.reduce(z, |x, y| x + y), Some(10));
+    assert_eq!(y.reduce(z, |x, y| x + y), Some(7));
+    assert_eq!(z.reduce(z, |x, y| x + y), None);
+}