How to unit test file permissions in NUnit?

Question

I'm trying to unit test file read operations. In this scenario I also need make sure that, if a particular user don't have read access he should get an exception...

But somehow I'm unable to get it working, can anyone suggest something?

PS: I'm using Rhino mock and NUnit

Answer 1

You could use Rhino.Mocks "Do" extension to throw a specific exception:

public delegate void ThrowExceptionDelegate();
mystub.Stub(x => x.ReadFile()).Do(new ThrowExceptionDelegate(delegate()
    { throw new IOException(); }
    ));

This would allow you to test your exception handling code.

Answer 2

You need to get a test in place which, in place of reading a file is using a mock that throws an exception instead of really reading a file. Then you can verify that the appropriate handling is triggered and things work out as they should.

If you need a better answer, you need to give an example of your classes and maybe the skeleton of the test you've written so far.

Answer 3

I'd go for a proper acceptance test - using mocks too much can be a bit dangerous. In this case it's easy to programmatically set + unset file permissions anyway.

I had a similar problem - wanted to test a permissions problem + came up with the following helper class to wrap the library API for messing around with file permissions

set file permissions for c:\\program files\\company\\app\\file for all users