Unit test which requires a file in Request.Files

I'm writing a unit test and the piece of code its testing requires that a file be in Request.Files.

In my controller I'm c开发者_运维知识库alling something called AddDocument(file) and the file is taken from Request.Files.

How do you achieve unit testing this? Isn't the Request only available in the controller?

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check out this blog by scott hanselman on the topic. its pretty informative and well written.