Move const tests for Ordering to library\core

Part of #76268

library/core/tests/cmp.rs

@@ -1,4 +1,7 @@
-use core::cmp::{self, Ordering::*};
+use core::cmp::{
+    self,
+    Ordering::{self, *},
+};
 
 #[test]
 fn test_int_totalord() {
@@ -116,3 +119,16 @@ fn test_user_defined_eq() {
     assert!(SketchyNum { num: 37 } == SketchyNum { num: 34 });
     assert!(SketchyNum { num: 25 } != SketchyNum { num: 57 });
 }
+
+#[test]
+fn ordering_const() {
+    // test that the methods of `Ordering` are usable in a const context
+
+    const ORDERING: Ordering = Greater;
+
+    const REVERSE: Ordering = ORDERING.reverse();
+    assert_eq!(REVERSE, Less);
+
+    const THEN: Ordering = Equal.then(ORDERING);
+    assert_eq!(THEN, Greater);
+}

src/test/ui/consts/const-ordering.rs

@@ -1,15 +0,0 @@
-// run-pass
-
-use std::cmp::Ordering;
-
-// the following methods of core::cmp::Ordering are const:
-//  - reverse
-//  - then
-
-fn main() {
-    const REVERSE : Ordering = Ordering::Greater.reverse();
-    assert_eq!(REVERSE, Ordering::Less);
-
-    const THEN : Ordering = Ordering::Equal.then(REVERSE);
-    assert_eq!(THEN, Ordering::Less);
-}