为 Epplus Excel 文件创建起订量

Question

我在这里的第一个问题。我查看了我的查询，但找不到有用的答案。

我的任务是为我的 excel 文件编写单元测试用例。我面临的问题是我们将 Epplus 用于 excel 文件，我不确定如何为此编写单元测试用例。我查了一下，发现我们也可以用 MOQ 来模拟。但是我再次找不到任何有用的链接来模拟使用 Epplus 的 excel 文件。我找到了这个链接Unit testing classes that use EPPlus，但我不确定如何实现它。

如果有人可以提供如何为 excel 文件编写简单单元测试的示例，我将不胜感激。测试可以是检查上传的文件是否为excel文件，检查excel是否为空等。

抱歉，目前我没有任何样品。我可以分享的是我正在读取excel文件的代码：

public class MyController : Controller
{
  [HttpPost("upload")]
  public async Task<IActionResult> UploadFile(IFormFile file)
  {
   JArray data = new JArray();
    using (ExcelPackage package = new ExcelPackage(file.OpenReadStream()))
    {
      ExcelWorksheet worksheet = package.Workbook.Worksheets[1];
      //Check if excel is empty.
      if (worksheet.Dimension == null)
      {
         return BadRequest("File is blank.");
      }
     data = Helper.CreateJson(worksheet);
                }
     return Ok(data);
  }
}

我创建了一个帮助类：

public static JArray CreateJson(ExcelWorksheet worksheet)
{
  JArray data = new JArray();
  JObject jobject = new JObject();

  int rowCount = worksheet.Dimension.End.Row;
  int colCount = worksheet.Dimension.End.Column;

    for (int row = 1; row <= rowCount; row++)
    {
       for (int col = 1; col <= colCount; col++)
        {
          var value = worksheet.Cells[row, col].Value;
          //Excel has 2 columns and I want to create a json from that.
          if (col == 1)              
          {
             jObject.Add("ID", rowValue.ToString());
          }
          else
          {
             jObject.Add("Name", rowValue.ToString());
          }
        }
         data.Add(jObject);
         jObject= new JObject();
     }
   return data;
}

这是我目前的测试课。

public class TestClass
{
    private MyController _controller;
    public TestClass()
    {
      _controller = new MyController (); 
    }

      [Fact]
    public void Upload_WhenCalled()
    {
        //var file = new FileInfo(@"C:\myfile.xlsx");
        //...what next?

        var file = new Mock<IFormFile>();
        var content = File.OpenRead(@"C:\myfile.xlsx");

        var result = _controller.UploadFile(file.Object);
        //When I debug it throws error "Object reference not set to an instance of an object."
    }
}

Answer 1

在这种情况下，模拟 IFormFile 以在您的测试中返回文件流并将其传递给被测操作。确保满足所有其他必要的依赖项。

public class TestClass {
    private MyController _controller;
    public TestClass() {
      _controller = new MyController (); 
    }

    [Fact]
    public void Upload_WhenCalled() {
        //Arrange
        var content = File.OpenRead(@"C:\myfile.xlsx");
        var file = new Mock<IFormFile>();
        file.Setup(_ => _.OpenReadStream()).Returns(content);

        //Act
        var result = _controller.UploadFile(file.Object);

        //Assert
        //...
    }
}

虽然这应该可以帮助您解决当前的问题，但您应该真正采纳其他答案所建议的关于将 ExcelPackage 的紧密耦合从控制器中抽象出来的建议，使其成为自己的关注点。将使控制器更容易单独进行单元测试。

您始终可以根据需要单独对包装器进行集成测试。

从当前控制器中抽象出来的接口的简化示例

public interface IExcelService {
    Task<JArray> GetDataAsync(Stream stream);
}

这将有一个镜像控制器中的代码的实现

public class ExcelService: IExcelService {
    public async Task<JArray> GetDataAsync(Stream stream) {
        JArray data = new JArray();
        using (ExcelPackage package = new ExcelPackage(stream)) {
            ExcelWorksheet worksheet = package.Workbook.Worksheets[1];
            if (worksheet.Dimension != null) {
                data = await Task.Run(() => createJson(worksheet));
            }
        }
        return data;
    }

    private JArray createJson(ExcelWorksheet worksheet) {
        JArray data = new JArray();
        int colCount = worksheet.Dimension.End.Column;  //get Column Count
        int rowCount = worksheet.Dimension.End.Row;     //get row count
        for (int row = 1; row <= rowCount; row++) {
            JObject jobject = new JObject();
            for (int col = 1; col <= colCount; col++) {
                var value = worksheet.Cells[row, col].Value;
                //Excel has 2 columns and I want to create a json from that.
                if (col == 1) {
                    jObject.Add("ID", rowValue.ToString());
                } else {
                    jObject.Add("Name", rowValue.ToString());
                }
                data.Add(jObject);
            }
        }
        return data;
    }
}

控制器现在可以简化为遵循Explicit Dependencies Principle

public class MyController : Controller {
    private readonly IExcelService excel;
    public MyController(IExcelService excel) {
        this.excel = excel;
    }

    [HttpPost("upload")]
    public async Task<IActionResult> UploadFile(IFormFile file) {
        JArray data = await excel.GetDataAsync(myFile.OpenReadStream());
        if(data.Count == 0)
            return BadRequest("File is blank.");
        return Ok(data);
    }
}

您将确保接口和实现已在 Startup 的依赖反转框架中注册

services.AddScoped<IExcelService, ExcelService>();

所以现在控制器只关心在运行时调用时它应该做什么。我没有理由处理实施问题

public class MyControllerTests {
    [Fact]
    public async Task Upload_WhenCalled() {
        //Arrange
        var content = new MemoryStream();
        var file = new Mock<IFormFile>();
        file.Setup(_ => _.OpenReadStream()).Returns(content);
        var expected = new JArray();
        var service = new Mock<IExcelService>();
        service
            .Setup(_ => _.GetDataAsync(It.IsAny<Stream>()))
            .ReturnsAsync(expected);

        var controller = new MyController(service.Object);

        //Act
        var result = await controller.UploadFile(file.Object);

        //Assert
        service.Verify(_ => _.GetDataAsync(content));
        //...other assertions like if result is OkContentResult...etc
    }
}

要进行涉及实际文件的集成测试，您可以测试服务

public class ExcelServiceTests {
    [Fact]
    public async Task GetData_WhenCalled() {
        //Arrange
        var stream = File.OpenRead(@"C:\myfile.xlsx");
        var service = new ExcelService();

        //Act
        var actual = await service.GetDataAsync(stream);

        //Assert
        //...assert the contents of actual data.
    }
}

现在可以单独测试每个问题。

Answer 2

您无需模拟 EPPlus 即可进行测试。您的重点应该是测试您的代码，而不是 EPPlus 本身。就像您不会测试您使用的任何其他库一样。因此，让您的代码使用 EPPlus 在内存中生成一个 Excel 文件并返回它。然后在您的测试中使用 EPPlus 来验证您对文件的断言。

这是一个要使用的模式示例：

public class MyReportGenerator : IReportGenerator
{
    /* implementation here */
}

public interface IReportGenerator
{
    byte[] GenerateMyReport(ReportParameters parameters);
}

[TestMethod]
public void TestMyReportGenerate()
{
    //arrange
    var parameters = new ReportParameters(/* some values */);
    var reportGenerator = new MyReportGenerator(/* some dependencies */);

    //act
    byte[] resultFile = reportGenerator.GenerateMyReport(parameters);

    //assert
    using(var stream = new MemoryStream(resultFile))
    using(var package = new ExcelPackage(stream))
    {
        //now test that it generated properly, such as:
        package.Workbook.Worksheets["Sheet1"].Cells["C6"].GetValue<decimal>().Should().Be(3.14m);
        package.Workbook.Worksheets["Sheet1"].Column(5).Hidden.Should().BeTrue();
    }  
}

上面的例子是使用Fluent Assertions library，虽然显然这不是必需的。