namespace Amphora.UnitTests
{
    public class Xorshift64Tests : UnitTestSharp.TestFixture
    {
        public class SeedCtorTests : UnitTestSharp.TestFixture
        {
            public void ReplacesAZeroSeedWithOne()
            {
                var zero = new Xorshift64(0);
                var one = new Xorshift64(1);

                CheckEqual(one.NextUInt64(), zero.NextUInt64());
            }
        }

        public class NextUInt64Tests : UnitTestSharp.TestFixture
        {
            public void MatchesTheRecurrenceFromSeedOne()
            {
                var generator = new Xorshift64(1);

                CheckEqual(1082269761UL, generator.NextUInt64());
                CheckEqual(0x100041060c011441UL, generator.NextUInt64());
                CheckEqual(0x9b1e842f6e862629UL, generator.NextUInt64());
                CheckEqual(0xf554f503555d8025UL, generator.NextUInt64());
            }
        }

        public class NextUInt32Tests : UnitTestSharp.TestFixture
        {
            public void IsTheUpperHalfOfTheNext64BitDraw()
            {
                var generator = new Xorshift64(1);
                generator.NextUInt64();
                generator.NextUInt64();

                CheckEqual(0x9b1e842fU, generator.NextUInt32());
                CheckEqual(0xf554f503U, generator.NextUInt32());
            }
        }
    }
}