Make ui test that are run-pass and do not test the compiler itself library tests

1 files changed, 33 insertions, 0 deletions

diff --git a/library/core/tests/ops.rs b/library/core/tests/ops.rs
index e9d595e65e2..53e5539fad9 100644
--- a/library/core/tests/ops.rs
+++ b/library/core/tests/ops.rs
@@ -1,4 +1,5 @@
 use core::ops::{Bound, Range, RangeFrom, RangeFull, RangeInclusive, RangeTo, RangeToInclusive};
+use core::ops::{Deref, DerefMut};
 
 // Test the Range structs and syntax.
 
@@ -197,3 +198,35 @@ fn range_structural_match() {
         _ => unreachable!(),
     }
 }
+
+// Test Deref implementations
+
+#[test]
+fn deref_mut_on_ref() {
+    // Test that `&mut T` implements `DerefMut<T>`
+
+    fn inc<T: Deref<Target = isize> + DerefMut>(mut t: T) {
+        *t += 1;
+    }
+
+    let mut x: isize = 5;
+    inc(&mut x);
+    assert_eq!(x, 6);
+}
+
+#[test]
+fn deref_on_ref() {
+    // Test that `&T` and `&mut T` implement `Deref<T>`
+
+    fn deref<U: Copy, T: Deref<Target = U>>(t: T) -> U {
+        *t
+    }
+
+    let x: isize = 3;
+    let y = deref(&x);
+    assert_eq!(y, 3);
+
+    let mut x: isize = 4;
+    let y = deref(&mut x);
+    assert_eq!(y, 4);
+}