Dapper/tests/Dapper.Tests/Helpers/TransactedConnection.cs

using System;
using System.Data;

namespace Dapper.Tests
{
    public class TransactedConnection : IDbConnection
    {
        private readonly IDbConnection _conn;
        private readonly IDbTransaction _tran;

        public TransactedConnection(IDbConnection conn, IDbTransaction tran)
        {
            _conn = conn;
            _tran = tran;
        }

        public string ConnectionString
        {
            get { return _conn?.ConnectionString ?? ""; }
#pragma warning disable CS8767 // Nullability of reference types in type of parameter doesn't match implicitly implemented member (possibly because of nullability attributes).
            set { _conn.ConnectionString = value; }
#pragma warning restore CS8767 // Nullability of reference types in type of parameter doesn't match implicitly implemented member (possibly because of nullability attributes).
        }

        public int ConnectionTimeout => _conn.ConnectionTimeout;
        public string Database => _conn.Database;
        public ConnectionState State => _conn.State;

        public IDbTransaction BeginTransaction(IsolationLevel il)
        {
            throw new NotImplementedException();
        }

        public IDbTransaction BeginTransaction() => _tran;

        public void ChangeDatabase(string databaseName) => _conn.ChangeDatabase(databaseName);

        public void Close() => _conn.Close();

        public IDbCommand CreateCommand()
        {
            // The command inherits the "current" transaction.
            var command = _conn.CreateCommand();
            command.Transaction = _tran;
            return command;
        }

        public void Dispose() => _conn.Dispose();

        public void Open() => _conn.Open();
    }
}