Agile Testing: A Practical Guide for Testers and Agile Teams

Teams need the right tools and processes to create and execute technology-facing tests that guide development. We’ll give some examples of the types of tools needed in the last section of this chapter.

The Purpose of Quadrant 1 Tests

Unit tests and component tests ensure quality by helping the programmer understand exactly what the code needs to do, and by providing guidance in the right design. They help the team to focus on the story that’s being delivered and to take the simplest approach that will work. Unit tests verify the behavior of parts as small as a single object or method [Meszaros, 2007]. Component tests help solidify the overall design of a deployable part of the system by testing the interaction between classes or methods.

Developing unit tests can be an essential design tool when using TDD. When an agile programmer starts a coding task, she writes a test that captures the behavior of a tiny bit of code and then works on the code until the test passes. By building the code in small test-code-test increments, the programmer has a chance to think through the functionality that the customer needs. As questions come up, she can ask the customer. She can pair with a tester to help make sure all aspects of that piece of code, and its communication with other units, are tested.

The term test-driven development misleads practitioners who don’t understand that it’s more about design than testing. Code developed test-first is naturally designed for testability. Quadrant 1 activities are all aimed at producing software with the highest possible internal quality.

When teams practice TDD, they minimize the number of bugs that have to be caught later on. Most unit-level bugs are prevented by writing the test before the code. Thinking through the design by writing the unit test means the system is more likely to meet customer requirements. When post-development testing time is occupied with finding and fixing bugs that could have been detected by programmer tests, there’s no time to find the serious issues that might adversely affect the business. The more bugs that leak out of our coding process, the slower our delivery will be, and in the end, it is the quality that will suffer. That’s why the programmer tests in Quadrant 1 are so critical. While every team should adopt practices that work for its situation, a team without these core agile practices is unlikely to benefit much from agile values and principles.

Supporting Infrastructure

Solid source code control, configuration management, and continuous integration are essential to getting value from programmer tests that guide development. They enable the team to always know exactly what’s being tested. Continuous integration gives us a way to run tests every time new code is checked in. When a test fails, we know who checked in the change that caused the failure, and that person can quickly fix the problem. Continuous integration saves time and motivates each programmer to run the tests before checking in the new code. A continuous integration and build process delivers a deployable package of code for us to test.

Agile projects that lack these core agile practices tend to turn into “mini-waterfalls.” The development cycles are shorter, but code is still being thrown “over the wall” to testers who run out of time to test because the code is of poor quality. The term waterfall isn’t necessarily derogatory. We’ve worked on successful “waterfall” projects where the programmers stringently automate unit tests, practice continuous integration, and use automated builds to run tests. These successful “waterfall” projects also involve customers and testers throughout the development cycle. When we code without appropriate practices and tools, regardless of what we call the process, we’re not going to deliver high-quality code in a timely manner.

Why Write and Execute These Tests?

We’re not going into any details here about how to do TDD, or the best ways to write unit and component tests. There are several excellent books on those subjects. Our goal is to explain why these activities are important to agile testers. Let’s explore some reasons to use technology-facing tests that support the team.

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