c# - 如何为 ASP.NET Core 中的单元/集成测试模拟 IFormFile？

Question

我想编写用于在 ASP.NET Core 中上传文件的测试，但似乎找不到一种很好的方法来模拟/实例化从 IFormFile 派生的对象。

关于如何做到这一点有什么建议吗？

Answer 1

假设你有一个 Controller ，比如......

public class MyController : Controller {
    public Task<IActionResult> UploadSingle(IFormFile file) {...}
}

...使用被测方法访问 IFormFile.OpenReadStream()。

从 ASP.NET Core 3.0 开始，使用 FormFile Class 的实例现在是 IFormFile 的默认实现。

下面是使用 FormFile 类进行相同测试的示例

[TestClass]
public class IFormFileUnitTests {
    [TestMethod]
    public async Task Should_Upload_Single_File() {
        //Arrange
       
        //Setup mock file using a memory stream
        var content = "Hello World from a Fake File";
        var fileName = "test.pdf";
        var stream = new MemoryStream();
        var writer = new StreamWriter(stream);
        writer.Write(content);
        writer.Flush();
        stream.Position = 0;

        //create FormFile with desired data
        IFormFile file = new FormFile(stream, 0, stream.Length, "id_from_form", fileName);
        
        MyController sut = new MyController();
        
        //Act
        var result = await sut.UploadSingle(file);

        //Assert
        Assert.IsInstanceOfType(result, typeof(IActionResult));
    }
}

在引入之前FormFile Class或者在不需要实例的情况下，您可以使用 Moq 创建测试模拟流数据的模拟框架。

[TestClass]
public class IFormFileUnitTests {
    [TestMethod]
    public async Task Should_Upload_Single_File() {
        //Arrange
        var fileMock = new Mock<IFormFile>();
        //Setup mock file using a memory stream
        var content = "Hello World from a Fake File";
        var fileName = "test.pdf";
        var ms = new MemoryStream();
        var writer = new StreamWriter(ms);
        writer.Write(content);
        writer.Flush();
        ms.Position = 0;
        fileMock.Setup(_ => _.OpenReadStream()).Returns(ms);
        fileMock.Setup(_ => _.FileName).Returns(fileName);
        fileMock.Setup(_ => _.Length).Returns(ms.Length);

        var sut = new MyController();
        var file = fileMock.Object;

        //Act
        var result = await sut.UploadSingle(file);

        //Assert
        Assert.IsInstanceOfType(result, typeof(IActionResult));
    }
}