{"id":8662,"date":"2017-09-25T22:20:50","date_gmt":"2017-09-26T03:20:50","guid":{"rendered":"https:\/\/daedtech.wpenginepowered.com\/?p=8662"},"modified":"2017-09-25T22:20:50","modified_gmt":"2017-09-26T03:20:50","slug":"unit-testing-enough","status":"publish","type":"post","link":"https:\/\/daedtech.com\/unit-testing-enough\/","title":{"rendered":"How Much Unit Testing is Enough?"},"content":{"rendered":"

Editorial note: I originally wrote this post for the TechTown blog. \u00a0You can check out the original here, at their site<\/a>. \u00a0While you’re there, have a look at their training and course offerings.<\/em><\/p>\n

I work as an independent consultant, and I also happen to have created a book and some courses about unit testing. \u00a0So I\u00a0field a lot of questions about the subject. \u00a0In fact, companies sometimes bring me in specifically to help their developers adopt the practice. \u00a0And those efforts usually fall into a predictable pattern.<\/p>\n

Up until the moment that I arrive, most of the developers have spent zero time unit testing. \u00a0But nevertheless, they have all found something<\/em> to occupy them full time at the office. \u00a0So they must now choose: do less of something else or start working overtime for the sake of unit testing.<\/p>\n

This choice obviously inspires little enthusiasm. \u00a0Most developers I meet in my travels are conscientious folks. \u00a0They’ve been giving it their all and so they interpret this new thing that takes them away from their duties as a hindrance. \u00a0And, in spite of signing a contract to bring me in, management harbors the same worry. \u00a0While they buy into the long term benefit, they fret the short term cost.<\/p>\n

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All of this leads to a very predictable question. \u00a0How much unit testing is enough?<\/p>\n

Clients invariably ask me this, and usually they ask it almost immediately. \u00a0They want to understand how to spend the minimum amount of time required to realize benefits, but not a second longer. \u00a0This way they can return to the pressing matters they’ve delayed for the sake of learning this new skill.<\/p>\n

<\/p>\n

Defining Unit Testing<\/h3>\n

Now, before we go any further, let’s establish a working definition of unit testing. \u00a0You might have something specific in mind when you hear this term, but it does cause a fair bit of confusion.<\/p>\n

For instance, early in my career, I remember a dev manager with a curious (to me) definition of unit testing. \u00a0He meant making changes to the application and then running it to see what happened. \u00a0He reasoned that if you’d just, say, added a new text box to a form, that addition represented a “unit.” \u00a0So next you would “unit test” by compiling and running the app and observing that it now, in fact, had your new text box. \u00a0Given his definition of the word unit, it’s hard to argue his semantics. \u00a0Nevertheless, I do not plan to use this definition.<\/p>\n

Instead, I’ll go with something much closer to Martin Fowler’s definition<\/a>\u00a0or what the folks at Industrial Logic call a microtest<\/a>. \u00a0The terminology gets confusing because of the vagueness of the term “unit.” \u00a0Let’s address this by thinking of a unit as a method\/function in your code. \u00a0You use unit tests to test methods in your code.<\/p>\n

Now, moving beyond that, we can describe their specific properties, so as not to confuse them with things like integration tests, system tests, and acceptance tests. \u00a0First, we’ll only talk about automated tests, which knocks the aforementioned dev manager’s definition right out. \u00a0In terms of scope, unit tests operate on pieces of code in your codebase in isolation, and they run\u00a0quickly<\/em>. \u00a0If it triggers a file write or a the coordination of many classes in your codebase, that’s not a unit test. \u00a0And, finally, done right, these things tend to be small — only a handful of lines of code each.<\/p>\n

How Teams Quantify Their Unit Testing<\/h3>\n

In my experience, teams in the early stages of adoption try to quantify the testing effort in one of three basic ways. \u00a0I’ll list those quickly and then describe them in more detail.<\/p>\n