using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Driver.Ab.Transport.Wire;
namespace ZB.MOM.WW.OtOpcUa.Driver.Ab.Transport.Tests.Wire;

public sealed class CipWriterTests
{
    [Fact]
    public void PatchU16_overwrites_an_already_written_word()
    {
        var w = new CipWriter().U16(0).U8(7);
        w.PatchU16(0, 0xABCD);
        w.ToArray().ShouldBe(new byte[] { 0xCD, 0xAB, 0x07 });
    }

    [Theory]
    [InlineData(-1)]
    [InlineData(2)]    // would straddle the end: only bytes 0..2 are written
    [InlineData(3)]
    [InlineData(100)]  // inside spare buffer capacity (256), but never written
    public void PatchU16_outside_the_written_range_throws(int offset)
    {
        var w = new CipWriter().U16(0).U8(7);
        Should.Throw<ArgumentOutOfRangeException>(() => w.PatchU16(offset, 1));
        w.ToArray().ShouldBe(new byte[] { 0, 0, 7 });   // nothing was patched
    }
}