Add const-ness tests for i32::signum

Author: ecstatic-morse

src/test/run-pass/const-int-sign.rs

@@ -1,11 +1,21 @@
+#![feature(const_int_sign)]
+
 const NEGATIVE_A: bool = (-10i32).is_negative();
 const NEGATIVE_B: bool = 10i32.is_negative();
-const POSITIVE_A: bool= (-10i32).is_positive();
-const POSITIVE_B: bool= 10i32.is_positive();
+const POSITIVE_A: bool = (-10i32).is_positive();
+const POSITIVE_B: bool = 10i32.is_positive();
+
+const SIGNUM_POS: i32 = 10i32.signum();
+const SIGNUM_NIL: i32 = 0i32.signum();
+const SIGNUM_NEG: i32 = (-42i32).signum();
 
 fn main() {
     assert!(NEGATIVE_A);
     assert!(!NEGATIVE_B);
     assert!(!POSITIVE_A);
     assert!(POSITIVE_B);
+
+    assert_eq!(SIGNUM_POS, 1);
+    assert_eq!(SIGNUM_NIL, 0);
+    assert_eq!(SIGNUM_NEG, -1);
 }