public void random_enumerable()
{
Assert.Throws<ArgumentNullException>(() => ((IEnumerable<IEntity>)null).Random());
Assert.Null(Enumerable.Empty<IEntity>().Random());
var first = new Entity { Id = 1 };
var second = new Entity { Id = 2 };
var entities = new IEntity[] { first, second };
Assert.Same(first, new IEntity[] { first }.Random());
Assert.Contains(entities.Random(), entities);
}
