add extra tests

Author: Neutron3529

src/libcore/tests/num/int_macros.rs

@@ -252,15 +252,42 @@ macro_rules! int_module {
                 assert_eq!($T::from_str_radix("-9", 2).ok(), None::<$T>);
             }
 
+
             #[test]
             fn test_pow() {
                 let mut r = 2 as $T;
-
                 assert_eq!(r.pow(2), 4 as $T);
                 assert_eq!(r.pow(0), 1 as $T);
+                assert_eq!(r.wrapping_pow(2), 4 as $T);
+                assert_eq!(r.wrapping_pow(0), 1 as $T);
+                assert_eq!(r.checked_pow(2), Some(4 as $T));
+                assert_eq!(r.checked_pow(0), Some(1 as $T));
+                assert_eq!(r.overflowing_pow(2), (4 as $T,false));
+                assert_eq!(r.overflowing_pow(0), (1 as $T,false));
+                assert_eq!(r.saturating_pow(2), 4 as $T);
+                assert_eq!(r.saturating_pow(0), 1 as $T);
+
+                r = MAX;
+                // use `^` to represent .pow() with no overflow.
+                // if itest::MAX == 2^j-1, then itest is a `j` bit int,
+                // so that `itest::MAX*itest::MAX == 2^(2*j)-2^(j+1)+1`,
+                // thussaturating_pow the overflowing result is exactly 1.
+                assert_eq!(r.wrapping_pow(2), 1 as $T);
+                assert_eq!(r.checked_pow(2), None);
+                assert_eq!(r.overflowing_pow(2), (1 as $T,true));
+                assert_eq!(r.saturating_pow(2), MAX);
+                //test for negative exponent.
                 r = -2 as $T;
-                assert_eq!(r.pow(2), 4 as $T);
                 assert_eq!(r.pow(3), -8 as $T);
+                assert_eq!(r.pow(0), 1 as $T);
+                assert_eq!(r.wrapping_pow(3), -8 as $T);
+                assert_eq!(r.wrapping_pow(0), 1 as $T);
+                assert_eq!(r.checked_pow(3), Some(-8) as $T);
+                assert_eq!(r.checked_pow(0), Some(1) as $T);
+                assert_eq!(r.overflowing_pow(3), (-8 as $T,false));
+                assert_eq!(r.overflowing_pow(0), (1 as $T,false));
+                assert_eq!(r.saturating_pow(3), -8 as $T);
+                assert_eq!(r.saturating_pow(0), 1 as $T);
             }
         }
     };