Implement Mul for Vector2D * scalar

src/lib.rs

@@ -1,4 +1,5 @@
 use std::ops::Add;
+use std::ops::Mul;
 use std::ops::Sub;
 
 #[derive(Clone, Copy, Eq, PartialEq)]
@@ -20,6 +21,14 @@ impl<T: Sub> Sub for Vector2D<T> {
     }
 }
 
+impl<T: Mul + Copy> Mul<T> for Vector2D<T> {
+    type Output = Vector2D<T::Output>;
+
+    fn mul(self, other: T) -> Vector2D<T::Output> {
+        Vector2D(self.0 * other, self.1 * other)
+    }
+}
+
 #[derive(Clone, Copy, Eq, PartialEq)]
 struct Vector3D<T>(T, T, T);
 
@@ -238,6 +247,69 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_vector2_multiply_zeroes_yields_zeroes() {
+        let a = Vector2D(0.0, 0.0);
+        let b = 0.0;
+        let c = a * b;
+        assert!(c.0 == 0.0);
+        assert!(c.1 == 0.0);
+    }
+
+    #[test]
+    fn test_vector2_multiplication_by_zero_yields_zeroes() {
+        let a = Vector2D(1.0, 2.0);
+        let b = 0.0;
+        let c = a * b;
+        assert!(c.0 == 0.0);
+        assert!(c.1 == 0.0);
+    }
+
+    #[test]
+    fn test_vector2_multiplication_identity() {
+        let a = Vector2D(1.0, 2.0);
+        let b = 1.0;
+        let c = a * b;
+        assert!(c.0 == a.0);
+        assert!(c.1 == a.1);
+    }
+
+    #[test]
+    fn test_vector2_multiplication_by_positive_float() {
+        let a = Vector2D(1.0, 2.0);
+        let b = 2.0;
+        let c = a * b;
+        assert!(c.0 == a.0 * 2.0);
+        assert!(c.1 == a.1 * 2.0);
+    }
+
+    #[test]
+    fn test_vector2_multiplication_by_negative_float() {
+        let a = Vector2D(1.0, 2.0);
+        let b = -2.0;
+        let c = a * b;
+        assert!(c.0 == a.0 * -2.0);
+        assert!(c.1 == a.1 * -2.0);
+    }
+
+    #[test]
+    fn test_vector2_multiplication_by_positive_int() {
+        let a = Vector2D(1, 2);
+        let b = 2;
+        let c = a * b;
+        assert!(c.0 == a.0 * 2);
+        assert!(c.1 == a.1 * 2);
+    }
+
+    #[test]
+    fn test_vector2_multiplication_by_negative_int() {
+        let a = Vector2D(1, 2);
+        let b = -2;
+        let c = a * b;
+        assert!(c.0 == a.0 * -2);
+        assert!(c.1 == a.1 * -2);
+    }
+
     #[test]
     fn test_vector3d_add_zeroes_yields_zeroes() {
         let a = Vector3D(0.0, 0.0, 0.0);