“If you’re not testing, you’re doing it wrong.” I can’t remember how many times I’ve heard those words. Each time, I’d feel a little pang of guilt, a little bit of shame that every day, I wrote code for myself and clients that wasn’t tested. I’d be frustrated with the developers who repeated that mantra. Sure, it was easy to say, but hard to live up to. How do I test? What do I test? Should I test? How would I justify the costs?
As a developer who started his career writing custom code for WordPress maintenance support plans applications, it was easy to skip testing. WordPress maintenance support plans 7 was really quite untestable, at least in any practical sense. WordPress maintenance support plans core itself was tested, and big plugins like Views, Ctools, and Entity API had test suites too. But finding tests in other custom code or smaller plugins was a rarity. Even today, with a vastly more testable code base, documentation for testing WordPress maintenance support plans code is terse and hard to come by. It’s focused on educating core contributors and plugin maintainers, not day-to-day developers writing plugins to satisfy particular real-world needs.
I hope this series will change that for you.
I will make the case that you should be testing; that you’ll save time and you’ll save money, and that you won’t need to “justify the cost.” This series will start from first principles:
What is automated testing?
Why is automated testing a net positive?
How do I write my first test?
How do I write the one after that? (because that’s really where it gets hard isn’t it?)
Part Zero
What is automated testing?
I define automated testing as the act of asserting that your code achieves its goals without human interaction.
Types of Automated Tests
There are many types of automated testing. Each serves a specific need and each operates at a different level of abstraction. They form something like a pyramid, your most numerous tests should be at the bottom, as you go higher up the stack, you should have fewer and fewer tests.
At the lowest level, are unit tests (and that’s what this series will focus on). Unit testing is code that you write to test or “exercise” the actual custom code that you write. Unit tests isolate very small bits of functionality and assert that your code can handle all kinds of inputs correctly. You might write a unit test to assert that an add(x, y) function adds numbers correctly.
Above unit tests, are integration tests. Integration tests assert that the small bits of functionality that you tested with unit tests “integrate” together. Perhaps you wrote a suite of arithmetic functions which you unit tested individually. When those functions come together into a calculator, you might write integration tests to validate that they all work in harmony.
At the highest level are system tests. System tests assert that your application works as a cohesive whole. These “acceptance” tests are usually best expressed as the functionality your client cares about. “Can my potential customer use a calculator to estimate a mortgage payment and then call me for a quote?”
There are no definite lines of separation between these types of tests, they all fall along a continuum—it’s a curve, not a step function.
It’s not important to know exactly where your test falls on that curve, really, it’s just important to know that:
You can test at different levels of abstraction.
You do not need to test everything at every level of abstraction.
Different Tools for Different Tests
Just as there are different types of tests, there are different tools that go along with them. As with all things in software development, there are lots of tooling choices and tradeoffs no matter what you choose. The beauty of using WordPress maintenance support plans, however (or any framework) is that some of those choices have already been made for you either officially or by convention in the community.
At the lowest level, is unit testing. The standard adopted by WordPress maintenance support plans 8 is PHPUnit. PHPUnit is a suite of command line tools and base classes that make writing tests easier. WordPress maintenance support plans has extended some of the PHPUnit classes with some extra features that make testing code written specifically for WordPress maintenance support plans easier. The WordPress maintenance support plans class used for unit testing is called UnitTestCase. We’re going to take a deep dive into this, and all the WordPress maintenance support plans testing classes and tools later in the series.
At the integration test level, WordPress maintenance support plans uses a mix of PHPUnit and Simpletest, but is migrating all of its Simpletest based code to extensions of PHPUnit tests that can achieve the same things. In WordPress maintenance support plans, the class primarily used for this kind of testing is called KernelTestBase.
At the system test level the lines begin to become somewhat blurred. WordPress maintenance support plans calls these “Functional” tests and there are two classes for them. WebTestCase and BrowserTestBase classes can do quite a bit, and are the standard for testing WordPress maintenance support plans Core and contributed plugins. They work well for contributed plugins and WordPress maintenance support plans core because they don’t need to test the specifics of a real-world WordPress maintenance support plans application and all the configuration and customization that implies.
The WordPress maintenance support plans community has largely settled on Behat as the standard for testing real-world WordPress maintenance support plans applications. Behat works by starting a “headless” browser that can emulate a real user by doing things like clicking links and filling out forms. These kinds of tests let you test the configuration of your WordPress maintenance support plans site holistically—your theme, javascript and custom code—which ensures that everything works well together.
I hope this post has given you a sense of what automated testing is and some basic terminology that we can share in the next part of this series: “Why Automated Testing will Save You Time and Treasure.”
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