diff --git a/src/robot.rs b/src/robot.rs
index a9d6e6a..bedefa3 100644
--- a/src/robot.rs
+++ b/src/robot.rs
@@ -4,6 +4,41 @@ pub struct Robot {
     id: u32,
     o: Orientation,
     p: Position,
+    i: Vec<char>,
+}
+
+impl Robot {
+    /// Create new `Robot` with given id, `Orientation`, `Position` and instructions.
+    fn new(id: u32, o: Orientation, p: Position, i: Vec<char>) -> Robot {
+        Robot { id, o, p, i }
+    }
+    /// Apply given instruction to a `Robot`.
+    fn execute_instruction(&mut self) {
+        match self.i.pop() {
+            Some(instruction) => match instruction {
+                'L' => 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' => 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' => 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,
+                },
+                _ => (), // never happens 😉
+            },
+            None => (),
+        }
+    }
 }
 
 /// Enum to store all possible orientations.
@@ -15,7 +50,49 @@ enum Orientation {
 }
 
 /// Struct to store robot position.
+#[derive(PartialEq, Eq, Hash)]
 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', 'F', 'L', 'F'],
+        );
+        let mut hash = std::collections::HashMap::new();
+        //hash.insert(&r.p, &r.id); // first insert while initializing.
+        hash.remove(&r.p); // remove before execute_instruction().
+        r.execute_instruction();
+        hash.insert(&r.p, &r.id); // second insert after moving.
+        assert_eq!(r.p.x, 1);
+        assert_eq!(r.p.y, 3);
+        r.execute_instruction();
+        r.execute_instruction();
+        assert_eq!(r.p.x, 0);
+        assert_eq!(r.p.y, 3);
+    }
+}