omg...

src/robot.rs

@@ -13,34 +13,30 @@ impl Robot {
         Robot { id, o, p, i }
     }
     /// Apply given instruction to a `Robot`.
-    fn execute_instruction(
+    fn execute_instruction(&mut self) {
-        &mut self,
-        hash: &mut std::collections::HashMap<Position, u32>,
-    ) -> Result<(), &'static str> {
-        hash.remove(&self.p); // we need to insert the new position after calling execute_instruction()
         match self.i.pop() {
             Some(instruction) => match instruction {
-                'L' => Ok(match self.o {
+                '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' => Ok(match self.o {
+                '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' => Ok(match self.o {
+                '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,
-                }),
-                _ => Err("Invalid instruction."),
                 },
-            None => Ok(()),
+                _ => (),
+            },
+            None => (),
         }
     }
 }
@@ -85,10 +81,18 @@ mod tests {
             0,
             Orientation::N,
             Position { x: 1, y: 2 },
-            vec!['R', 'L', 'F', 'F'],
+            vec!['R', 'F', 'L', 'F'],
         );
-        assert!(r.execute_instruction().is_ok());
+        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);
     }
 }