Why Query successfully executed while postgresql's connection state is closed?

I have followed Mocking insert query to a MySQL Database using Moq as a guideline to do moq. In my case, I will do moq with postgesql.

Test case is passed. However, I have a question: why "Update query successfully executed" is shown while postgresql's connection state is closed? Is it as expected result when we do moq? If it's not expected result, what should I do?

Thanks in advance.

Here is Console's result After running this test.

UPDATE DEVICES SET user_id=null WHERE camera_id = 'G41140'

Update query succesfully executed.

This is a part of my code

   [Test, Order(1)]
  public void UpdateTest()
        {
            //Arrange

            DumpDatabase databaseSetting = new DumpDatabase();
            //Assume, fill the right setting for db
            databaseSetting.Host = "***.***.*.**";
            databaseSetting.Port = "****";
            databaseSetting.Database = "*****";
            databaseSetting.UserName = "******";
            databaseSetting.Password = "***********";

            var commandMock = new Mock<IDbCommand>();
            commandMock
                .Setup(m => m.ExecuteNonQuery())
                .Verifiable();

            var connectionMock = new Mock<IDbConnection>();
            connectionMock
                .Setup(m => m.CreateCommand())
                .Returns(commandMock.Object);

            var connectionFactoryMock = new Mock<IDbConnectionFactory>();
            connectionFactoryMock
                .Setup(m => m.CreateConnection())
                .Returns(connectionMock.Object);
            var sut = new DumpConnection(connectionFactoryMock.Object, databaseSetting);
            // Act
            sut.Update();
            // Assert
            commandMock.Verify();


        }

 public class DumpConnection : IDbConnectionFactory
    {
        DumpDatabase _databaseSetting;

        private IDbConnectionFactory connectionFactory;
        public DumpConnection(IDbConnectionFactory connectionFactory, DumpDatabase databaseSetting)
        {
            this.connectionFactory = connectionFactory;
            this._databaseSetting = databaseSetting;
        }

        public IDbConnection CreateConnection()
        {
            return new NpgsqlConnection("Server=" + _databaseSetting.Host + ";User Id=" + _databaseSetting.UserName + "; " +
  "Password=" + _databaseSetting.Password + ";Database=" + _databaseSetting.Database + ";");
        }

        public void Update()
        {
            string query = "UPDATE DEVICES SET user_id=null WHERE camera_id = 'G41140' ";
            Console.WriteLine(query);
            using (var connection = connectionFactory.CreateConnection())
            {

                //Creates and returns a MySqlCommand object associated with the MySqlConnection. 
                using (var command = connection.CreateCommand())
                {
                    command.CommandText = query;
                    Console.WriteLine("Established connection");
                    Console.WriteLine("State Before open : " + connection.State);
                    connection.Open();
                    Console.WriteLine("State After open : " + connection.State);
                    Console.WriteLine("Update query succesfully executed.");
                }
            }
        }

    }

    public interface IDbConnectionFactory
    {
        IDbConnection CreateConnection();

    }