// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2;
using Xunit;
 
namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests;
 
public class BitShifterTests
{
    [Fact]
    public void WriteUInt31BigEndian_PreservesHighestBit()
    {
        // Arrange
        Span<byte> dirtySpan = new byte[] { 0xff, 0xff, 0xff, 0xff };
 
        // Act
        Bitshifter.WriteUInt31BigEndian(dirtySpan, 1);
 
        Assert.Equal(new byte[] { 0x80, 0x00, 0x00, 0x01 }, dirtySpan.ToArray());
    }
 
    [Fact]
    public void WriteUInt31BigEndian_True_PreservesHighestBit()
    {
        // Arrange
        Span<byte> dirtySpan = new byte[] { 0xff, 0xff, 0xff, 0xff };
 
        // Act
        Bitshifter.WriteUInt31BigEndian(dirtySpan, 1, true);
 
        Assert.Equal(new byte[] { 0x80, 0x00, 0x00, 0x01 }, dirtySpan.ToArray());
    }
 
    [Fact]
    public void WriteUInt31BigEndian_False_OverwritesHighestBit()
    {
        // Arrange
        Span<byte> dirtySpan = new byte[] { 0xff, 0xff, 0xff, 0xff };
 
        // Act
        Bitshifter.WriteUInt31BigEndian(dirtySpan, 1, false);
 
        Assert.Equal(new byte[] { 0x00, 0x00, 0x00, 0x01 }, dirtySpan.ToArray());
    }
}