I'm doing some job interviews for the first time for my replacement. I want to know how they would approach a brownfields project, but am not really sure how to phrase the question.
I'd like to know what their attitude is: e.g. throw out and rewrite, use a tool to refactor, step through the code and understand, what books they've read (e.g. "Working Effectively with Legacy Code").
How do you find out how someone takes on brownfields software development?
This sounds like a great interview question. Why not just ask them what steps they'd take on inheriting/maintaining/extending a badly written legacy codebase, or how do you determine when a codebase needs to be refactored? Another option would be to give them a medium sized piece of spaghetti code and ask them how they'd extend it.
Lots of good suggestions for answers here.
When interviewing, try to engage in scenario brainstorming or role playing, not definition swapping. In this case try to engage an applicant in telling their story about what they would expect "...when taking over responsibility for the main finance system, which this department and that group use daily for these things, and there are a couple things that are wrong with it today, and oh by the way, there is a upgrade release scheduled for three months from now that will allow direct integration with this new banking partner for 1099 processing". Make the scenario specific and real for your situation, and get them talking.
The important thing is to draw out from them not only what they would do, but almost as importantly, what they know to expect. If your candidate sits across from you and weaves a story about getting up to speed in a couple days and making major changes up through production by next Friday, without asking any of the important questions and impressing you with their effectiveness, doubt their experience (and if you are in a regulated industry or, unfortunately, Big Company, possibly their sanity). If instead they ask good questions about what the environment is like today, what's the review process, who makes the decisions about functionality, is there a testing environment, is the code testable or are there unit tests (gasp) in place, and what happens today if a change needs to get in place by Friday - hey, they've probably been here and done this before.
You of course want to hear how they would make sure existing functionality works and time bombs aren't being set but you also want to hear them making reference to things they would be doing so that this project becomes better, easier to work with, and more fun over time. The activities they specifically are engaging in to turn the inherited legacy project into a rocking world of fun should come through in their storytelling. I mean, they are planning on doing that, right?
Great interviews are conversations and experience sharing and story telling. Draw those stories out, bounce them against the b.s. shield, and go.