X10D/X10D.Tests/src/IO/StreamTests.cs

using System.Diagnostics;
using System.Security.Cryptography;
using System.Text;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using X10D.IO;

namespace X10D.Tests.IO;

[TestClass]
public class StreamTests
{
    [TestMethod]
    public void GetHashSha1ShouldBeCorrect()
    {
        // SHA-1
        byte[] expectedHash =
        {
            0x0A, 0x4D, 0x55, 0xA8, 0xD7, 0x78, 0xE5, 0x02, 0x2F, 0xAB, 0x70, 0x19, 0x77, 0xC5, 0xD8, 0x40, 0xBB, 0xC4, 0x86,
            0xD0
        };

        using var stream = new MemoryStream();
        stream.Write(Encoding.UTF8.GetBytes("Hello World"));
        stream.Position = 0;

        byte[] hash = stream.GetHash<SHA1>();
        Trace.WriteLine($"Hash: {BitConverter.ToString(hash)}");
        Trace.WriteLine($"Expected: {BitConverter.ToString(expectedHash)}");
        CollectionAssert.AreEqual(expectedHash, hash);
    }

    [TestMethod]
    public void GetHashNullShouldThrow()
    {
        // any HashAlgorithm will do, but SHA1 is used above. so to remain consistent, we use it here
        Assert.ThrowsException<ArgumentNullException>(() => ((Stream?)null)!.GetHash<SHA1>());
        Assert.ThrowsException<ArgumentNullException>(() => ((Stream?)null)!.TryWriteHash<SHA1>(Span<byte>.Empty, out _));
    }

    [TestMethod]
    public void TryWriteHashSha1ShouldBeCorrect()
    {
        // SHA-1
        byte[] expectedHash =
        {
            0x0A, 0x4D, 0x55, 0xA8, 0xD7, 0x78, 0xE5, 0x02, 0x2F, 0xAB, 0x70, 0x19, 0x77, 0xC5, 0xD8, 0x40, 0xBB, 0xC4, 0x86,
            0xD0
        };

        using var stream = new MemoryStream();
        stream.Write(Encoding.UTF8.GetBytes("Hello World"));
        stream.Position = 0;

        Span<byte> hash = stackalloc byte[20];
        stream.TryWriteHash<SHA1>(hash, out int bytesWritten);
        Assert.AreEqual(expectedHash.Length, bytesWritten);
        CollectionAssert.AreEqual(expectedHash, hash.ToArray());
    }
}