public void TestCreateIsVisible(Vector location, bool expected)
{
var min = Vector.Create(5, 5);
var max = Vector.Create(15, 15);
Func <Vector, Vector> mapper =
vector => Vector.Create(vector.X - min.X, vector.Y - min.Y);
var viewPort = ImmutableGrid <bool>
.CreateBuilder(max.X - min.X + 1, max.Y - min.Y + 1)
.Set(5, 5, true)
.Build();
var isVisible = LineOfSight
.CreateIsVisible(min, max, mapper, viewPort)(location);
Assert.AreEqual(expected, isVisible);
}