Add explicit tests for doubles

Author: mattico

src/float/add.rs

@@ -226,6 +226,13 @@ mod test {
         assert_eq!(r, tiny + tiny);
     }
 
+    #[test]
+    fn test_double_tiny_plus_tiny() {
+        let tiny = f64::from_repr(1);
+        let r = super::__adddf3(tiny, tiny);
+        assert_eq!(r, tiny + tiny);
+    }
+
     #[test]
     fn test_float_small_plus_small() {
         let a = f32::from_repr(327);
@@ -234,12 +241,26 @@ mod test {
         assert_eq!(r, a + b);
     }
 
+    #[test]
+    fn test_double_small_plus_small() {
+        let a = f64::from_repr(327);
+        let b = f64::from_repr(256);
+        let r = super::__adddf3(a, b);
+        assert_eq!(r, a + b);
+    }
+
     #[test]
     fn test_float_one_plus_one() {
         let r = super::__addsf3(1f32, 1f32);
         assert_eq!(r, 1f32 + 1f32);
     }
 
+    #[test]
+    fn test_double_one_plus_one() {
+        let r = super::__adddf3(1f64, 1f64);
+        assert_eq!(r, 1f64 + 1f64);
+    }
+
     #[test]
     fn test_float_nan() {
         let r = super::__addsf3(f32::NAN, 1.23);