anchor.diff:    expect(direction.y, equals(y));
   }
   
  +void testAddToMainDirections(DirectionSystem directionSystem, List directions, List<Map> expectedDirections, bool doNullMainDirection) {
  +  for (int i = 0; i < directions.length; i++) {
  +    directionSystem.addToMainDirection(directions[i]);
  +    testDirection(directionSystem.mainDirection, expectedDirections[i]["x"], expectedDirections[i]["y"]);
  +    if (doNullMainDirection) directionSystem.nullMainDirection();
  +  }
  +}
  +
   num _makeRadians(num angles) => angles * (PI / 180);
  
positive.code:       testDirection(directionSystem.rightDirection, 1, 0);
      });
      test("Default diagonal directions", () {
        testDirection(directionSystem.upLeftDirection, -SQRT2_2, -SQRT2_2);
        testDirection(directionSystem.upRightDirection, SQRT2_2, -SQRT2_2);
        testDirection(directionSystem.downLeftDirection, -SQRT2_2, SQRT2_2);
        testDirection(directionSystem.downRightDirection, SQRT2_2, SQRT2_2);
      });
    });
  
    group("AddtoMainDirection", (){});
  
    group("SetMainDirection", (){});
  
    group("GetDirection", (){});
  
    group("NullMainDirection", (){});
  
    group("rotateDirections", (){});
  
  }
  
  
negative.code: 
  import 'package:unittest/unittest.dart';
  import 'package:dartrocket/src/physics.dart';
  import 'package:dartrocket/src/constant.dart' show Direction;
  import 'dart:math';
  
  void main() => defineTest();
  
  //Calculated with Wolfram Alpha: http://www.wolframalpha.com/input/?i=sqrt%282%29%2F2
  const expectedDiagonalValue = 0.7071067811865475244008443621048490392848359376884740;
  
  void defineTest() {
  
  