如何将工厂模式应用于对数据库的调用

Question

负责对数据库进行调用的服务：

public class DbClient : IDbClient
{
    private readonly IOptions<DbSettings> _dbSettings;

    public DbClient(IOptions<DbSettings> dbSettings)
    {
        _dbSettings = dbSettings;
    }

    public List<EmployeeDataModel> GetEmployees()
    {
        using (SqlConnection connection = new SqlConnection(_dbSettings.Value.ConnectionString))
        {
            connection.Open();
            return connection.GetAll<EmployeeDataModel>().ToList();
        }
    }

    public void InsertEmployee(EmployeeDataModel employee)
    {
        using (SqlConnection connection = new SqlConnection(_dbSettings.Value.ConnectionString))
        {
            connection.Open();
            connection.Insert(employee);
        }
    }

    public void DeleteEmployee(int id)
    {
        using (SqlConnection connection = new SqlConnection(_dbSettings.Value.ConnectionString))
        {
            connection.Open();
            connection.Delete( new EmployeeDataModel() {Id = id });
        }
    }

    public void EditEmployee(EmployeeDataModel employee)
    {
        using (SqlConnection connection = new SqlConnection(_dbSettings.Value.ConnectionString))
        {
            connection.Open();
            connection.Update(employee);
        }
    }
}

它只是执行简单的CRUD操作。

问题：此服务无法轻松进行集成测试。原因？它在每个方法内创建SQL连接（这是第一个问题，我只想在创建问题的地方放一个地方），并且无法使用事务范围模拟此SQL连接（以回滚集成测试）。在这种情况下如何应用工厂模式？

Answer 1

将IDbConnection注入到您的构造函数中，并在创建服务时让工厂传递该连接。这是一个例子：

public class SqlService
{
    private IDbConnection _connection;

    public SqlService(IDbConnection connection)
    {
        _connection = connection;
    }

    public void DoSql()
    {
        using (_connection)
        {
            _connection.Open();
            // Do sql
            // Also assuming that .GetAll is an IDbConnection extension from your ORM.
        }
    }
}
public class TestFactory
{
    private bool _isTestMode;

    public TestFactory(bool isTestMode)
    {
        _isTestMode = isTestMode;
    }

    public SqlService GetSqlService()
    {
        if (_isTestMode)
        {
            var connectionToMockData = // mock data connection

            return new SqlService(connectionToMockData);
        }
        else
        {
            var sqlConnection = new SqlConnection(_dbSettings.Value.ConnectionString);

            return new SqlService(sqlConnection);
        }
    }
}