public void AddToX_WorksWithNegativeNumber()
{
testCoordinate = new Coordinate(1, 1);
testCoordinate.AddToX(-2);
Assert.AreEqual(-1, testCoordinate.X);
}
public void AddToX_WorksWithPositiveNumber()
{
testCoordinate = new Coordinate(1, 1);
testCoordinate.AddToX(1);
Assert.AreEqual(2, testCoordinate.X);
}