public void Test_S2_GoodFastHashSpreads()
{
int kTestPoints = 1 << 16;
var set = new List <int>();
var points = new SortedSet <S2Point>();
var base_ = new S2Point(1, 1, 1);
for (var i = 0; i < kTestPoints; ++i)
{
// All points in a tiny cap to test avalanche property of hash
// function (the cap would be of radius 1mm on Earth (4*10^9/2^35).
S2Point perturbed = base_ + S2Testing.RandomPoint() / (1UL << 35);
perturbed = perturbed.Normalize();
set.Add(perturbed.GetHashCode());
points.Add(perturbed);
}
// A real collision is extremely unlikely.
Assert.Equal(0, kTestPoints - points.Count);
// Allow a few for the hash.
Assert.True(10 >= kTestPoints - set.Count);
}