如何模拟连接到 MS Access 数据库的方法

Question

我下面有一个示例方法，它检查table是否被占用。这是我第一次做单元测试，读到单元测试只是孤立的代码，对数据库执行的任何操作都应该被模拟出来，否则它就变成了集成测试。不过，如果有人能指出正确的方向，我不太确定如何去嘲笑它。

 public bool isTableOccupied(string tableID)
 {
     bool tableOccupied = false;
     try
     {
         connection.Open();
         using (OleDbCommand command = new OleDbCommand())
         {
              command.Connection = connection;
              command.CommandText = "SELECT [Occupied] FROM [Table] WHERE [TableID] =@TableID";
              command.Parameters.AddRange(new OleDbParameter[] {
                  new OleDbParameter("@TableID", tableID)
                  });
                  OleDbDataReader reader = command.ExecuteReader();

                  while (reader.Read())
                  {
                      if (reader["Occupied"].ToString() == "True")
                      {
                          tableOccupied = true;
                      }
                  }
          }
          connection.Close();
      }
      catch (Exception ex)
      {
           MessageBox.Show("Error " + ex);
      }
      return tableOccupied;
}

Answer 1

为了模拟单元测试的方法，您需要创建一个您的 class 应该实现的接口，例如：

public interface IRepository
{
    bool IsTableOccupied(string tableId);
}

public class ExampleRepository : IRepository
{
    public bool IsTableOccupied(string tableID)
    {
        // Your data access code goes here.
    }
}

其次，你应该"inject"将Interface的实例"inject"放入父调用代码的方法或class中，例如：

public class ExampleBusiness
{
    private readonly IRepository repository;

    public ExampleBusiness(IRepository repository)
    {
        this.repository = repository;
    }

    public bool IsTableOccupied(string tableId)
    {
        return this.repository.IsTableOccupied(tableId);
    }
}

然后您可以编写单元测试并实施模拟框架（例如 Moq）来模拟您的 "isTableOccupied" 方法，例如：

// Create mock.
var mockRepository = new Mock<IRepository>();

// Setup to return the desired mock value. In this case, return true if any string tableId is provided.
mockRepository.Setup(x => x.IsTableOccupied(It.IsAny<string>())).Returns(true);

// Call the parent method and inject the mock.
var testBusiness = new ExampleBusiness(mockRepository.Object);

// Finally, assert that the value is as expected.
Assert.IsTrue(testBusiness.IsTableOccupied("TestId");

如何模拟连接到 MS Access 数据库的方法

How to mock a method connecting to an MS Access database

c#

ms-access

unit-testing

mocking