tnsu-approval-route/backend/tests/Tnsu.ApprovalRoute.IntegrationTests/Infrastructure/PostgresDatabaseFixture.cs

using Microsoft.EntityFrameworkCore;
using Npgsql;
using Tnsu.ApprovalRoute.Infrastructure.Persistence;
using Xunit;

namespace Tnsu.ApprovalRoute.IntegrationTests.Infrastructure;

// Отдельная БД на один xUnit-collection (= один тестовый класс) в общем инстансе Postgres.
// Тесты внутри класса делят эту БД; разные классы (разные коллекции) получают разные БД.
public sealed class PostgresDatabaseFixture : IAsyncLifetime
{
    private readonly string _databaseName = $"tnsu_test_{Guid.NewGuid():N}";
    private readonly NpgsqlConnectionStringBuilder _adminConnectionBuilder = new(TestSettings.BaseConnectionString);

    public string ConnectionString { get; private set; } = string.Empty;

    public async Task InitializeAsync()
    {
        await using (var adminConnection = new NpgsqlConnection(_adminConnectionBuilder.ConnectionString))
        {
            await adminConnection.OpenAsync();
            await using var createCommand = new NpgsqlCommand($"CREATE DATABASE \"{_databaseName}\"", adminConnection);
            await createCommand.ExecuteNonQueryAsync();
        }

        ConnectionString = new NpgsqlConnectionStringBuilder(_adminConnectionBuilder.ConnectionString)
        {
            Database = _databaseName
        }.ConnectionString;

        var options = new DbContextOptionsBuilder<ApprovalRouteDbContext>()
            .UseNpgsql(ConnectionString)
            .UseSnakeCaseNamingConvention()
            .Options;

        await using var db = new ApprovalRouteDbContext(options);
        await db.Database.MigrateAsync();
    }

    public async Task DisposeAsync()
    {
        await using var adminConnection = new NpgsqlConnection(_adminConnectionBuilder.ConnectionString);
        await adminConnection.OpenAsync();

        await using (var terminateCommand = new NpgsqlCommand(
            """
            SELECT pg_terminate_backend(pid) FROM pg_stat_activity
            WHERE datname = @databaseName AND pid <> pg_backend_pid();
            """,
            adminConnection))
        {
            terminateCommand.Parameters.AddWithValue("databaseName", _databaseName);
            await terminateCommand.ExecuteNonQueryAsync();
        }

        await using var dropCommand = new NpgsqlCommand($"DROP DATABASE IF EXISTS \"{_databaseName}\"", adminConnection);
        await dropCommand.ExecuteNonQueryAsync();
    }
}