Round negative signed integer towards zero in iN::midpoint

library/core/tests/num/midpoint.rs

@@ -0,0 +1,54 @@
+//! Test the following expectations:
+//!  - midpoint(a, b) == (a + b) / 2
+//!  - midpoint(a, b) == midpoint(b, a)
+//!  - midpoint(-a, -b) == -midpoint(a, b)
+
+#[test]
+#[cfg(not(miri))]
+fn midpoint_obvious_impl_i8() {
+    for a in i8::MIN..=i8::MAX {
+        for b in i8::MIN..=i8::MAX {
+            assert_eq!(i8::midpoint(a, b), ((a as i16 + b as i16) / 2) as i8);
+        }
+    }
+}
+
+#[test]
+#[cfg(not(miri))]
+fn midpoint_obvious_impl_u8() {
+    for a in u8::MIN..=u8::MAX {
+        for b in u8::MIN..=u8::MAX {
+            assert_eq!(u8::midpoint(a, b), ((a as u16 + b as u16) / 2) as u8);
+        }
+    }
+}
+
+#[test]
+#[cfg(not(miri))]
+fn midpoint_order_expectation_i8() {
+    for a in i8::MIN..=i8::MAX {
+        for b in i8::MIN..=i8::MAX {
+            assert_eq!(i8::midpoint(a, b), i8::midpoint(b, a));
+        }
+    }
+}
+
+#[test]
+#[cfg(not(miri))]
+fn midpoint_order_expectation_u8() {
+    for a in u8::MIN..=u8::MAX {
+        for b in u8::MIN..=u8::MAX {
+            assert_eq!(u8::midpoint(a, b), u8::midpoint(b, a));
+        }
+    }
+}
+
+#[test]
+#[cfg(not(miri))]
+fn midpoint_negative_expectation() {
+    for a in 0..=i8::MAX {
+        for b in 0..=i8::MAX {
+            assert_eq!(i8::midpoint(-a, -b), -i8::midpoint(a, b));
+        }
+    }
+}

library/core/tests/num/mod.rs

@@ -28,6 +28,7 @@ mod dec2flt;
 mod flt2dec;
 mod int_log;
 mod int_sqrt;
+mod midpoint;
 mod ops;
 mod wrapping;