namespace Just.PreciseMath.Tests;

public class DoubleDoubleRootFunctionsTests
{
    [Fact]
    public void ExistingRootsAreAvailableOnTheTypeAndMatchFacadeBits()
    {
        DoubleDouble[] values = [DoubleDouble.Zero, DoubleDouble.NegativeZero,
            DoubleDouble.NaN, DoubleDouble.PositiveInfinity, DoubleDouble.NegativeInfinity,
            new(-1.0), new(double.Epsilon), new(2.0), new(double.MaxValue),
            DoubleDouble.FromComponents(1.0, Math.ScaleB(1.0, -1000))];
        foreach (DoubleDouble value in values)
        {
            AssertBits(DDMath.Sqrt(value), DoubleDouble.Sqrt(value));
            AssertBits(DDMath.InvSqrt(value), DoubleDouble.InvSqrt(value));
        }
    }

    private static void AssertBits(DoubleDouble expected, DoubleDouble actual)
    {
        BitConverter.DoubleToInt64Bits(actual.High).ShouldBe(BitConverter.DoubleToInt64Bits(expected.High));
        BitConverter.DoubleToInt64Bits(actual.Low).ShouldBe(BitConverter.DoubleToInt64Bits(expected.Low));
    }
}