create and move robot + tests

src/robot.rs

@@ -1,9 +1,44 @@
 /// A Robot *aka droid* is represented here.
 /// Each robot must have a unique id.
 pub struct Robot {
-    id: u32,
+    id: i32,
     o: Orientation,
     p: Position,
+    i: Vec<char>,
+}
+
+impl Robot {
+    /// Create new `Robot` with given id, `Orientation`, `Position` and instructions.
+    fn new(id: i32, o: Orientation, p: Position, i: Vec<char>) -> Robot {
+        Robot { id, o, p, i }
+    }
+    /// Apply given instruction to a `Robot`.
+    fn execute_instruction(&mut self) -> Result<(), &'static str> {
+        match self.i.pop() {
+            Some(instruction) => match instruction {
+                'L' => Ok(match self.o {
+                    Orientation::N => self.o = Orientation::W,
+                    Orientation::E => self.o = Orientation::N,
+                    Orientation::S => self.o = Orientation::E,
+                    Orientation::W => self.o = Orientation::S,
+                }),
+                'R' => Ok(match self.o {
+                    Orientation::N => self.o = Orientation::E,
+                    Orientation::E => self.o = Orientation::S,
+                    Orientation::S => self.o = Orientation::W,
+                    Orientation::W => self.o = Orientation::N,
+                }),
+                'F' => Ok(match self.o {
+                    Orientation::N => self.p.y += 1,
+                    Orientation::E => self.p.x += 1,
+                    Orientation::S => self.p.y -= 1,
+                    Orientation::W => self.p.x -= 1,
+                }),
+                _ => Err("Invalid instruction."),
+            },
+            None => Ok(()),
+        }
+    }
 }
 
 /// Enum to store all possible orientations.
@@ -19,3 +54,36 @@ struct Position {
     x: i32,
     y: i32,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_new_robot() {
+        let r: Robot = Robot::new(
+            0,
+            Orientation::N,
+            Position { x: 1, y: 2 },
+            vec!['L', 'L', 'F', 'R'],
+        );
+        assert_eq!(r.id, 0);
+        assert!(matches!(r.o, Orientation::N));
+        assert_eq!(r.p.x, 1);
+        assert_eq!(r.p.y, 2);
+        assert_eq!(r.i, vec!['L', 'L', 'F', 'R']);
+    }
+
+    #[test]
+    fn test_execute_instruction() {
+        let mut r: Robot = Robot::new(
+            0,
+            Orientation::N,
+            Position { x: 1, y: 2 },
+            vec!['R', 'L', 'F', 'F'],
+        );
+        assert!(r.execute_instruction().is_ok());
+        assert_eq!(r.p.x, 1);
+        assert_eq!(r.p.y, 3);
+    }
+}