public void IsResultValid_VerticesFromCoordinates_InvalidInput()
{
var service = new TriangleService();
var input = new TriangleCoordinate('z', 2);
var result = service.GetVerticesForCoordinate(input);
Assert.Null(result);
input = new TriangleCoordinate('a', -2);
result = service.GetVerticesForCoordinate(input);
Assert.Null(result);
}