The Code-Free Developer Interview

When it comes to evaluating candidates for software engineering roles, it's hard to keep up with the latest and greatest techniques. We know logic puzzles don't work. Writing pseudocode on a white board is so tired and cliche at this point that companies brag about not doing that. Teams have resorted to what seems like an obvious choice at first blush: just have the candidate write some code. This new trend may have some unintended consequences, though.

Presented at RailsConf 2018 in Pittsburgh, PA on April 18, 2018.

Transcript

1. The Code-Free
   Developer Interview
   Pete Holiday
   @toomuchpete
   

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2. The Code-Free Developer Interview @toomuchpete
   

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3. The Code-Free Developer Interview @toomuchpete
   My Goal For This Session:
   ERADICATE CODING INTERVIEWS
   

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4. The Code-Free Developer Interview @toomuchpete
   What is a “Coding Interview”
   • Reviewing Code Samples or GitHub Profiles
   • Code Tests (Codility, etc)
   • Code Challenges
   • Live Coding or Pair Programming
   

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5. The Code-Free Developer Interview @toomuchpete
   Disfavored Interview Techniques
   • Whiteboarding
   • “Clever” Riddles
   • Language Trivia
   
   

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6. The Code-Free Developer Interview @toomuchpete
   Why Interview with Code?
   

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7. The Code-Free Developer Interview @toomuchpete
   The big lie of coding
   interviews is that they
   don’t replicate real work.
   

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8. The Code-Free Developer Interview @toomuchpete
   The Problem With Coding Interviews
   • Disadvantage people without a lot of free time
   • Live coding and pairing are stressful
   • They’re difficult to develop and maintain
   • Many passive candidates just won’t do take home tests
   

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9. The Code-Free Developer Interview @toomuchpete
   What Should We Do Instead?
   Talk to the candidates
   

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10. The Code-Free Developer Interview @toomuchpete
    General Interviewing Tips
    • Define what you’re looking for ahead of time
    • Ask all candidates a consistent set of questions
    • Interviewers should write down their thoughts before discussing them
    • Interviewing is a skill that must be developed and practiced
    

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11. The Code-Free Developer Interview @toomuchpete
    Dig Into Their Experience
    

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12. The Code-Free Developer Interview @toomuchpete
    Dig Into Their Experience
    • “What was your role on this project?”
    • “How does that system/feature work?”
    • “Where’s the worst technical debt in this project?” “How would you fix
    it?” “Why hasn’t the team fixed it yet?”
    • “Has it had any bugs our outages in production?” “What happened?”
    “How did the team fix it?”
    

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13. The Code-Free Developer Interview @toomuchpete
    Have Them do Review Code
    

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14. The Code-Free Developer Interview @toomuchpete
    Selecting Code to Review
    • Avoid production code
    • Actively reduce complexity
    • Include realistic bugs, but don’t emphasize Bug Hunts
    • Best Options:
    • Completely contrived (maybe your old code challenge?)
    • Open Source Repo with a contrived Pull Request
    

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15. The Code-Free Developer Interview @toomuchpete
    Evaluating a Code Review
    • Bad Pull Request or Commit Habits
    • Non-idiomatic Code
    • Overly Complex code (things that need refactors)
    • Bad/confusing naming of variables or methods
    • Overly architected classes / YAGNI
    • Actual Bugs (Bonus Points Only)
    

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16. The Code-Free Developer Interview @toomuchpete
    Collaborative System Design
    
    
    

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17. The Code-Free Developer Interview @toomuchpete
    What is “Collaborative System Design”?
    • Hypothetically Build a Tool, Platform, or Project
    • No Code or Pseudocode
    • Work With The Candidate
    • Usually Pretty Quick
    

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18. The Code-Free Developer Interview @toomuchpete
    How To Pick A CSD Project
    • Should be easy to understand
    • Excellent if your company’s software has an obvious use case
    • Related to the skills you’re hiring for; Rails is very different from Angular
    • When in doubt, pick something generally well-known
    

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19. The Code-Free Developer Interview @toomuchpete
    General Tips for Running CSD
    • Time-box the exercise; tell them they won’t “finish” the design
    • Pre-populate boring, boilerplate sections ()
    • Let the candidate lead
    • If the candidate is moving fast or seems comfortable, increase complexity
    

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20. The Code-Free Developer Interview @toomuchpete
    Case Study:

    Let’s Build Facebook!
    

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21. The Code-Free Developer Interview @toomuchpete
    Build Facebook: The MVP
    • Get Rid of Boilerplate: We Have Users and Auth Already
    • What’s Included in a Facebook Clone MVP?
    • Friending
    • Status Updates / Feed
    • Caution: Likes, Comments
    • “Where would we start to build out this MVP?”
    

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22. The Code-Free Developer Interview @toomuchpete
    Build Facebook: Status Updates
    • “How do we implement status updates?”
    • Go Deeper: How do we implement basic privacy controls?
    • Even Deeper: What about granular privacy controls?
    • Keep Digging: How do we solve the obvious performance problem?
    

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23. The Code-Free Developer Interview @toomuchpete
    Build Facebook: Friending
    • “How do we implement friendship status?”
    • What do we do about the bi-directional nature?
    • How do we implement requests?
    • How do we add blocking?
    

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24. The Code-Free Developer Interview @toomuchpete
    Should You Ever Resort to a
    Coding Interview?
    

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25. The Code-Free Developer Interview @toomuchpete
    When To Use Coding Interviews
    • Weak interviewer skills; this should be temporary
    • Determining whether entry-level candidates can program at all
    • When a very specific programming skill might determine seniority
    • Your organization mandates Pair Programming
    • When you’re transitioning to code-free (❄)
    

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26. The Code-Free Developer Interview @toomuchpete
    I believe we’ll come to
    see coding interviews as
    an anti-pattern.
    

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27. The Code-Free Developer Interview @toomuchpete
    THANK YOU!
    

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