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: }
  
  void testDirectionRange(direction, startX, endX, startY, endY) {
    expect(direction.x, inExclusiveRange(startX, endX));
    expect(direction.y, inExclusiveRange(startY, endY));
  }
  
  void testAddToMainDirection(DirectionSystem directionSystem, List directions, List<Map> expectedDirections, bool doNullMainDirection) {
  
negative.code:   for (int i = 0; i < directions.length; i++) {
      testDirection(directionSystem.getDirection(directions[i]), expectedDirections[i]["x"], expectedDirections[i]["y"]);
    }
  }