anchor.diff:        directionSystem = null;
       });
       test("Testing main directions", () {
  -      testAddToMainDirection(directionSystem, Direction.MAIN_DIRECTIONS, [{
  -          "x": 0,
  -          "y": -1
  -        }, {
  -          "x": 0,
  -          "y": 1
  -        }, {
  -          "x": -1,
  -          "y": 0
  -        }, {
  -          "x": 1,
  -          "y": 0
  -        }], true);
  +      testAddToMainDirection(directionSystem, Direction.MAIN_DIRECTIONS, 
  +          [{"x": 0,"y": -1}, {"x": 0,"y": 1},
  +           {"x": -1,"y": 0}, {"x": 1,"y": 0}], true);
       });
       test("Testing diagonal directions", () {
  -      testAddToMainDirection(directionSystem, Direction.DIAGONAL_DIRECTIONS, [{
  -          "x": -expectedDiagonalValue,
  -          "y": -expectedDiagonalValue
  -        }, {
  -          "x": expectedDiagonalValue,
  -          "y": -expectedDiagonalValue
  -        }, {
  -          "x": -expectedDiagonalValue,
  -          "y": expectedDiagonalValue
  -        }, {
  -          "x": expectedDiagonalValue,
  -          "y": expectedDiagonalValue
  -        }], true);
  +      testAddToMainDirection(directionSystem, Direction.DIAGONAL_DIRECTIONS, 
  +          [{"x": -expectedDiagonalValue,"y": -expectedDiagonalValue},
  +           {"x": expectedDiagonalValue,"y": -expectedDiagonalValue},
  +           {"x": -expectedDiagonalValue,"y": expectedDiagonalValue},
  +           {"x": expectedDiagonalValue,"y": expectedDiagonalValue}], true);
       });
     });
   
  
positive.code:     });
      test("Rotate 45 angles diagonal directions", () {
        directionSystem.rotateDirectionsAngles(45);
        testDirection(directionSystem.upLeftDirection, -1, 0);
        testDirection(directionSystem.upRightDirection, 1, 0);
        testDirection(directionSystem.downLeftDirection, 0, -1);
        testDirection(directionSystem.downRightDirection, 0, 1);
      });
      test("Rotate 90 angles main directions", () {
        directionSystem.rotateDirectionsAngles(90);
        testDirection(directionSystem.upDirection, 1, 0);
        testDirection(directionSystem.downDirection, -1, 0);
        testDirection(directionSystem.leftDirection, 0, -1);
        testDirection(directionSystem.rightDirection, 0, 1);
      });
    });
  
  }
  
  void testDirection(direction, x, y) {
    expect(direction.x, equals(x));
  
negative.code:       directionSystem = null;
      });
      test("Testing diagonal directions", () {
        testSetMainDirection(directionSystem, Direction.MAIN_DIRECTIONS, 
            [{"x": 0,"y": -1}, {"x": 0,"y": 1},
             {"x": -1,"y": 0}, {"x": 1,"y": 0}]);
      });
      test("Testing diagonal directions", () {
        testSetMainDirection(directionSystem, Direction.DIAGONAL_DIRECTIONS, 
            [{"x": -expectedDiagonalValue,"y": -expectedDiagonalValue},
             {"x": expectedDiagonalValue,"y": -expectedDiagonalValue},
             {"x": -expectedDiagonalValue,"y": expectedDiagonalValue},
             {"x": expectedDiagonalValue,"y": expectedDiagonalValue}]);
      });
    });
  
  