Separation of Duties in Scrum Software Development

The following excerpt is a thread from a discussion on Linkedin in the CISSP group.  I repost it because I think that it is an important consideration for organizations incorporating agile techniques into their Software Development Life Cycle (SDLC). 

Date: October 5, 2010

Question:

I am looking for some input on “separation of duties” and “access control” concerns in regard with the SCRUM software development model.

My R&D team is running a pilot on SCRUM. The developers on the pilot team test each other code (apparently both unit and system testing), have access to the QA environment, etc. They believe it is a standard practice for SCRUM.

Thoughts, comments, practical recommendations?

Ken Hartman:

Ideally you would have a separate person/team installing the code on a QA box. This would ensure that the essential documentation and “packaging” is in place because you have a different set of hands touching it. Besides the security benefit, the other advantage of separation of duties is that it must be packaged better. We (Visonex) roll up several sprints into a quarterly release. Only after you have the code deployment nailed on the QA server is it ready to be deployed into production (Ideally by a third person/team).

If you are doing SCRUM, a ‘must read’ book is Agile Testing by Crispin & Gregory. Among other things, the book introduces “Agile Testing Quadrants” and talks about the various tests and which team member should be doing them.

Question:

Code promotion from Dev to QA – I agree, code promotion needs to be controlled. We can try to put some process in place to restrict code promotion to QA only. May not be easy though if developers are also to QA (testing often require write access), but should be possible.

What are your thoughts on developers to perform integration testing? Any concern that it violates the segregation of duties principle? The same person, who developed new code, will be testing the code?

Ken Hartman:

Good points . I should clarify what I meant. Each SCRUM user story, according to the authors of the book that I cited, should list the tests that the new functionality should pass at the time that each user story is created. The developers definitely need to test their code before passing it on to QA. In fact, some software development systems can be configured to require that the code pass the corresponding unit test before it can be checked back into the source control system.

I think that having the developer create the automated unit tests that proves that they coded the functionality per the user story causes the developer to create higher quality code. The developers should run every test (including integration testing) they need to so as to prove that their functionality:

  1. Meets the new user stories, and
  2. Didn’t break anything that was working—but they need to do this on an anonymized server under their control.

Then, and only then, should it be passed to QA. When I stated above that the code needed to be properly packaged, I meant that if the code is not sufficiently documented so that a QA person can deploy it to their QA environment without needing a developer to tweak it, then the code package should be rejected back to development. This is essential for adequate configuration management. If a developer has to tweak things on the QA system, do you really have configuration management?

Now, the QA function should run all of the same unit tests that were created by the developer but this time on the anonymized QA environment. This way, the QA function is verifying the adequacy of the unit tests in addition to the program code. However, the QA function should not ever fix the program code or the automated unit tests—it needs to be sent back to development and repackaged.

QA can and should run additional tests (these are mentioned in the Agile Testing book) that include usability, performance, load, stress, and scalability but one of the main qoals of the QA function is to make sure that everything is packaged up properly, meets the requirements and is ready for production.

In summary, developers should definitely do testing before the hand off to QA. QA should verify that development tested adequately. Preventing QA from making fixes increases transparency and achieves separation of duties.

Tagged , , , , , , , , , , , , . Bookmark the permalink.
  • The postings and views on this site are my own and do not necessarily reflect the positions, strategies, or opinions of any current or previous employer.