RED: test executing command sequences

test/mars_rover_test.dart

@@ -92,5 +92,41 @@ void main() {
         expect(rover.y, equals(0));
       });
     });
+
+    group('Executing Command Sequences:', () {
+      test('single command L', () {
+        final rover = Rover(x: 0, y: 0, direction: 'N');
+        rover.execute('L');
+        expect(rover.direction, equals('W'));
+      });
+
+      test('single command R', () {
+        final rover = Rover(x: 0, y: 0, direction: 'N');
+        rover.execute('R');
+        expect(rover.direction, equals('E'));
+      });
+
+      test('single command M', () {
+        final rover = Rover(x: 0, y: 0, direction: 'N');
+        rover.execute('M');
+        expect(rover.y, equals(1));
+      });
+
+      test('complex sequence MMRMMLM', () {
+        final rover = Rover(x: 0, y: 0, direction: 'N');
+        rover.execute('MMRMMLM');
+        expect(rover.x, equals(2));
+        expect(rover.y, equals(3));
+        expect(rover.direction, equals('N'));
+      });
+
+      test('example from Mars Rover kata', () {
+        final rover = Rover(x: 1, y: 2, direction: 'N');
+        rover.execute('LMLMLMLMM');
+        expect(rover.x, equals(1));
+        expect(rover.y, equals(3));
+        expect(rover.direction, equals('N'));
+      });
+    });
   });
 }