don't hardcode return value in forward()

src/main.rs

@@ -9,7 +9,10 @@ mod rover {
     type Rover = (i32, i32, Facing);
 
     pub fn forward(r : Rover) -> Rover {
-	(1 as i32, 0 as i32, Facing::N)
+	match r {
+	    (lon, lat, direction) =>
+		(lon as i32, lat - 1 as i32, direction)
+	}
     }
 }
 
@@ -18,10 +21,13 @@ mod tests {
     use super::*;
 
     #[test]
-    fn rover_run() {
-	assert_eq!(1,1);
+    fn move_north() {
 	let r = (1 as i32, 1 as i32, rover::Facing::N);
 	assert_eq!(rover::forward(r),
 		   (1 as i32, 0 as i32, rover::Facing::N));
+
+	let r = (1 as i32, 3 as i32, rover::Facing::N);
+	assert_eq!(rover::forward(r),
+		   (1 as i32, 2 as i32, rover::Facing::N));
     }
 }