prefab-page-detail/Prefab.Tests/Infrastructure/Aspire/AppHost.cs

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;

namespace Prefab.Tests.Infrastructure.Aspire;

internal sealed class AppHost(DistributedApplication application, EnvironmentVariableScope? environmentScope) : IAsyncDisposable
{
    public DistributedApplication Application => application;

    public static async Task<AppHost> StartAsync(IReadOnlyDictionary<string, string?>? environmentOverrides, CancellationToken cancellationToken)
    {
        EnvironmentVariableScope? scope = null;
        if (environmentOverrides is not null && environmentOverrides.Count > 0)
        {
            scope = new EnvironmentVariableScope(environmentOverrides);
        }

        DistributedApplication? application = null;
        try
        {
            string[] defaultArgs =
            [
                "SqlServer:UseDataVolume=false",
                "SqlServer:HostPort=",
                "Parameters:prefab-sql-password=PrefabTests!1234",
            ];

            var builder = await DistributedApplicationTestingBuilder
                .CreateAsync<Projects.Prefab_AppHost>(defaultArgs, static (_, hostOptions) =>
                {
                    hostOptions ??= new HostApplicationBuilderSettings();
                    hostOptions.Configuration ??= new ConfigurationManager();
                }, cancellationToken);

            application = await builder.BuildAsync(cancellationToken);
            await application.StartAsync(cancellationToken);

            var notifications = application.ResourceNotifications;
            await notifications.WaitForResourceHealthyAsync("prefab-sql", cancellationToken);
            await notifications.WaitForResourceHealthyAsync("prefab-catalog", cancellationToken);
            await notifications.WaitForResourceHealthyAsync("prefab-web", cancellationToken);
            
            return new AppHost(application, scope);
        }
        catch
        {
            if (application is not null)
            {
                await application.DisposeAsync();
            }

            scope?.Dispose();
            throw;
        }
    }

    public HttpClient CreateHttpClient(string resourceName) =>
        application.CreateHttpClient(resourceName);

    public async Task<string> GetSqlConnectionStringAsync(string resourceName, CancellationToken cancellationToken)
    {
        var connectionString = await application.GetConnectionStringAsync(resourceName, cancellationToken).ConfigureAwait(false);
        if (string.IsNullOrWhiteSpace(connectionString))
        {
            throw new InvalidOperationException($"SQL resource '{resourceName}' did not provide a connection string.");
        }

        return connectionString;
    }

    public async ValueTask DisposeAsync()
    {
        try
        {
            await application.StopAsync(CancellationToken.None);
        }
        catch
        {
            // best effort
        }

        await application.DisposeAsync();
        environmentScope?.Dispose();
    }
}

internal sealed class EnvironmentVariableScope : IDisposable
{
    private readonly IReadOnlyDictionary<string, string?> _overrides;
    private readonly Dictionary<string, string?> _originalValues = new(StringComparer.OrdinalIgnoreCase);

    public EnvironmentVariableScope(IReadOnlyDictionary<string, string?> overrides)
    {
        _overrides = overrides;

        foreach (var pair in overrides)
        {
            _originalValues[pair.Key] = Environment.GetEnvironmentVariable(pair.Key);
            Environment.SetEnvironmentVariable(pair.Key, pair.Value);
        }
    }

    public void Dispose()
    {
        foreach (var pair in _overrides)
        {
            _originalValues.TryGetValue(pair.Key, out var value);
            Environment.SetEnvironmentVariable(pair.Key, value);
        }
    }
}