// 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 System.Collections;
using System.Collections.Generic;
using Microsoft.Build.Internal;
using Shouldly;
using Xunit;
 
namespace Microsoft.Build.UnitTests;
 
public class CommunicationUtilitiesTests
{
    /// <summary>
    /// Verify our custom way of getting env vars gives the same results as the BCL.
    /// </summary>
    [Fact]
    public void GetEnvVars()
    {
        IDictionary<string, string> envVars = CommunicationsUtilities.GetEnvironmentVariables();
        IDictionary referenceVars = Environment.GetEnvironmentVariables();
        IDictionary<string, string> referenceVars2 = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
 
        foreach (DictionaryEntry item in referenceVars)
        {
            referenceVars2.Add((string)item.Key!, (string)item.Value!);
        }
 
        Helpers.AssertCollectionsValueEqual(envVars, referenceVars2);
    }
 
    /// <summary>
    /// Verify that we correctly restore environment variables.
    /// </summary>
    [Fact]
    public void RestoreEnvVars()
    {
        string testName1 = "_MSBUILD_TEST_ENV_VAR1";
        string testName2 = "_MSBUILD_TEST_ENV_VAR2";
 
        // A long value exceeding the former limit of 32,767 characters.
        string testValue = new string('a', 1_000_000);
 
        CommunicationsUtilities.SetEnvironmentVariable(testName1, testValue);
        try
        {
            IDictionary<string, string> envVars = CommunicationsUtilities.GetEnvironmentVariables();
 
            CommunicationsUtilities.SetEnvironmentVariable(testName1, null);
            CommunicationsUtilities.SetEnvironmentVariable(testName2, testValue);
 
            CommunicationsUtilities.SetEnvironment(envVars);
 
            Environment.GetEnvironmentVariable(testName1).ShouldBe(testValue);
            Environment.GetEnvironmentVariable(testName2).ShouldBe(null);
        }
        finally
        {
            CommunicationsUtilities.SetEnvironmentVariable(testName1, null);
            CommunicationsUtilities.SetEnvironmentVariable(testName2, null);
        }
    }
}