What Is A Complete Feature: A Developer's Perspective

16 July 2017 on . 5 minutes to read

What is a complete feature, and how does that affect your team and product?

As a developer, what does a complete feature mean? This is a question that should be answered both as an individual and for the team or organization as whole. Part of being a cohesive team revolves around everyone being on the same page regarding what constitutes completeness. A higher level of completeness ensures that your customers, developers and managers will be happier since they’ll enable you to do things correctly the first time. Delivery of polished items is how key stakeholders are impressed and kept coming back for more or, in the case of budget makers, approving bigger and better things for your team.

The different levels

Read on for the different levels of completeness. Each level encompasses the previous levels and describes what’s needed to break through for increased operational efficiency and product reliability.

Level 1: Feature Functionality is 100%

This is the most basic level of completeness. The developer in question has built out the code neccessary to complete a feature; this typically involves manual testing in a development environment to ensure that it works as expected.

Level 2: Full Unit Test Coverage

Hopefully all the code in your codebase meets at least this level of completeness. Here, all committed code has 100% coverage via unit tests. This is the bare minimum needed to ensure that:

1) Each function does what’s expected 2) Should there be edge cases, they can be easily added to coverage so you can ensure they aren’t repeated

Level 3: Manual Feature Testing with Permutations

The next level involves a more formal QA process around the feature, with acceptance from someone who isn’t the developer. This ensures there are a second set of eyes on the functionality and also helps spot unintended side effects that the dev may not have noticed. It’s typical for a developer to do operations the same way every time, so if there’s another path to accomplish the same thing, a dev may not think about testing it as, in their minds, “Why would someone do it that way?”. I also include code reviews here. At this level it’s all about having extra sets of eyes and different approaches to the same feature that way you can be as sure as possible that all your bases are covered.

Level 4: Full Integration Coverage

Adding full integration coverage for a feature is the closest you can come to being sure that your feature behaves as expected end-to-end and that it stays that way. Doing full manual regressions across every feature in your application every deploy just isn’t feasible; that’s why you need integration tests. The QA team will focus their attention towards the most critical items in your application but will rarely hit every permutation of a feature. Each user is unique, and the users of your application will always find a way to do things which you didn’t anticipate. Should they be able to break something, it’s important that you’re able to replicate it. Most well run codebases fall within this tier of completeness.

Level 5: Feature Has Complete Documentation

Adding documentation to your code is an oft overlooked aspect of feature completeness. Maintaining good documentation is key for certain areas of your app which aren’t easily apparent to a new dev picking up the project. This is particulary true for the following:

  • Complicated user workflows
  • Specific restrictions or limitations and why they are in place (ie, do we limit users to X items in a SaaS app because of performance, business or paid tiering?)
  • API endpoints (speicifically Protocol, URL, Port, Payload and Return Values)
  • Programming patterns, why they developed that way and how they’re helpful
  • Custom code which replicates commonly used libraries (was there a reason you wrote your own Delayed::Job implementation and extensions rather than using Sidekiq?)
  • Internal processes
  • How to access/trigger key functionality within the codebase
  • Bootstrapping the app for a new dev
  • Deployment process

All points of code are fair game for documentation. The above however are what I currently consider the bare minimum for maintaing a good bus factor.

Level 6: Instrumentation Around Key Metrics Are Present

Finally is instrumentation. This refers to sending metrics about key parts of your app off to a service so that you can set up alerts, graphs and monitors around the counts, execution times and usage patterns of your application. A well put together dashboard and alert system will save you a bunch of trouble as it enables you to address many problem points before they negatively impact all your users. Being able to quickly respond to, mitigate and clean up hot spots is what seperates a good operation from an excellent, tightly run ship.

Level N + 1

This list is by no means meant to be the be all, end all of what completeness entails. Always be on the lookout for identfying new ways to increase your code quality.

The Takeaway

There are always ways to put out more complete features. Be aware of them and put out the best code possible for your business and timeline constraints. Keep them in mind when dedicating to feature development and how they’ll alter your development pace. Remember, more time spent upfront on these will reduce code churn in the future, make for less problems in production and enable you to more quickly address any issues which do arise.


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