How to upload a file to an endpoint from an integration test

Question

When a file is uploaded from the client, it can be found in this.Request.Files, which is of type HttpFileCollectionBase.

HttpFileCollectionBase contains HttpPostedFileBase entries.

The properties on these objects are read-only, so I was hoping I could setup some mocks. My mock request would return a mock HttpFileCollection, and that collection would contain one mockHttpPostedFile. The InputStream property on that object would return a FileStream object that I would instantiate using a real file in source control.

1. Is this a good approach to uploading a file to an endpoint from an integration test?
2. If it is a good approach, how can I mock this out with Moq?
3. If this is not a good approach, can you suggest a better way?

Thanks!

Answer 1

I know nothing about asp.net mvc, but it looks like you would need to do something like this to setup your mock dependencies:

MemoryStream stream = new MemoryStream();

var mockFile = new Mock<HttpPostedFileBase>();
var mockFiles = new Mock<HttpFileCollectionBase>();
var mockRequest = new Mock<HttpRequestBase>();

mockFile.Setup(f => f.InputStream).Returns(stream);

// if for example, you index the file by name.
mockFiles.Setup(f => f[It.IsAny<string>()]).Returns(mockFile.Object);

mockRequest.Setup(r => r.Files).Returns(() => mockFiles.Object);

// write expected data to your memory stream, then instantiate your class 
// under test using the mockRequest.Object

In a unit test, I would use a memory stream rather a file, but a file stream works the same.

If you want to avoid having to mock out and set up all these dependencies, you could put them behind a UploadedFiles abstraction, make your code depend on the abstraction, and mock only UploadedFiles. This need only be a thin wrapper around Request.Files to get a file stream by name (or however you access them). This is better because the downstream code now depends on UploadedFiles, Stream and string, rather than HttpRequestBase, HttpFileCollectionBase, HttpPostedFileBase, Stream and string.

Setup would then be simplified to something like this:

MemoryStream stream = new MemoryStream();
var mockUploadedFiles = new Mock<UploadedFiles>();
mockUploadedFiles.Setup(u => u.GetFile(It.IsAny<string>())).Returns(stream);