C# Unit Test How to mocK IFormFileCollection?

Question

I have a method that uses IFormFileCollection and i want to unit test it.

my method :

public IActionResultUploadBankAccount(){

 IFormFileCollection files = Request.Form.Files;
                if (!files.Any()) return Ok(new GeneralDto.Response("Check your files!"));
 // and my codes

}

and my authorize codes :

MockAuthorize.cs :

public static void Authorize(this ControllerBase controller,....){

//my codes
 var bytes = Encoding.UTF8.GetBytes("This is a text file");
            IFormFile file = new FormFile(new MemoryStream(bytes), 0, bytes.Length, "Data", @"\Mock\Images\testFile.jpg");


}

while i'm trying to test it, method throws error that says:

System.NullReferenceException : Object reference not set to an instance of an object.

What am i doing wrong? or is there any way to test FormFileCollection?

Answer 1

As FormFileCollection is part of .NET, you shouldn't be testing it. Microsoft will have tested this functionality.

All you should be testing is your own logic.

In order to mock IFormFileCollection I would use a mocking framework such as Moq and do something like this

private Mock<IFormFileCollection> _formFileCollectionMock;
private IClassToTest _sut;

public YourConstructor()
{
    _formFileCollectionMock= new Mock<IFormFileCollection>();
    _sut = new ClassToTest(_formFileCollectionMock.Object);
}