Creating an instance of HttpPostedFileBase for unit testing

Question

I need to create an instance of HttpPostedFileBase class object and pass it to a method, but I cannot find any way to instantiate it. I am creating a test case to test my fileupload method.

This is my method which takes an HttpPostedFileBase object. I need to call it from my test case class. I am not using any mock library.

Is there a simple way to do this?

[HttpPost]
public JsonResult AddVariation(HttpPostedFileBase file, string name, string comment, string description, decimal amount, string accountLineTypeID)
{
    var accountLineType = _fileService.GetAccountLineType(AccountLineType.Debit);
    if (Guid.Parse(accountLineTypeID) == _fileService.GetAccountLineType(AccountLineType.Credit).AccountLineTypeID)
    {
        amount = 0 - amount;
    }
    var info = new File()
    {
        FileID = Guid.NewGuid(),
        Name = name,
        Description = description,
        FileName = file.FileName,
        BuildID = Guid.Parse(SelectedBuildID),
        MimeType = file.ContentType,
        CreatedUserID = CurrentUser.UserID,
        UpdatedUserID = CurrentUser.UserID,
        Amount = amount,
    };
    var cmmnt = new Comment()
    {
        CommentDate = DateTime.Now,
        CommentText = comment,
        FileID = info.FileID,
        UserID = CurrentUser.UserID
    };
    _variationService.AddVariation(info, file.InputStream);
    _variationService.AddComment(cmmnt);
    return Json("Variation Added Sucessfully", JsonRequestBehavior.AllowGet);
}

Answer 1

HttpPostedFileBase is an abstract class so therefore it cannot be directly instantiated.

Create a class that derives from HttpPostedFileBase and returns the values you are looking for.

    class MyTestPostedFileBase : HttpPostedFileBase
{
Stream stream;
string contentType;
string fileName;

public MyTestPostedFileBase(Stream stream, string contentType, string fileName)
{
    this.stream = stream;
    this.contentType = contentType;
    this.fileName = fileName;
}

public override int ContentLength
{
    get { return (int)stream.Length; }
}

public override string ContentType
{
    get { return contentType; }
}

public override string FileName
{
    get { return fileName; }
}

public override Stream InputStream
{
    get { return stream; }
}

public override void SaveAs(string filename)
{
    throw new NotImplementedException();
}
}

Answer 2

I think that @BenjaminPaul has the best answer - but wanted to add this in case anyone else is looking to test the content length on the MyTestPostedFileBase object.

I created the class as is outlined above and then passing a stream that is filled with random bytes - this allows the `MyTestPostedFileBase.ContentLength to return a testable value that I needed.

byte[] byteBuffer = new Byte[10];
Random rnd = new Random();
rnd.NextBytes(byteBuffer);
System.IO.MemoryStream testStream = new System.IO.MemoryStream(byteBuffer);

and then instantiate it:

var TestImageFile = new MyTestPostedFileBase(testStream, "test/content", "test-file.png");