Precision and reliability have become two of the most important principals in software development. Few things can be as vexing as flaky tests. These elusive anomalies, as their name suggests, are the tests that play hide-and-seek with developers, passing and failing without rhyme or reason. While their whimsical nature may seem harmless at first glance, the issue actually has a major impact on software quality, developer morale, and overall project success.

What are flaky tests?

To gauge the size of the problem, organizations must understand what flaky tests are. Flaky tests are the bane of a developer’s existence, behaving inconsistently and unpredictably. They can pass successfully one moment and then fail inexplicably the next, all without any alterations to the underlying code. This can damage the base of a software toolchain, destroying trust in the testing process and causing significant frustration among developers.

Flaky tests can show up in several ways. They may be affected by the environment that  they run in, sensitive to the order in which tests are executed, or simply influenced by the seemingly random occurrences. This unpredictability makes them particularly challenging to diagnose and address.

Impact on software quality and developer morale

The consequences of flaky tests are bigger than developer annoyance. They bring a serious threat to software quality. When tests that should reliably catch bugs start failing intermittently, developers may become desensitized to failures, assuming them to be yet another fluke. As a result, legitimate issues can slip through the cracks, leading to lower-quality software releases.

Flaky tests will also disrupt the flow of developers’ work. The frustration of encountering these unreliable tests can sap morale and motivation. Time and energy are wasted investigating false alarms, hindering progress and causing demotivation. Developer morale is a critical factor in a project’s success, and flaky tests can erode it with surprising speed.

Why should you address flaky tests?

It is important to recognize that flaky tests are not minor as they often lead to critical problems that demand attention. Ignoring these tests can have severe consequences, affecting software quality and the happiness and satisfaction of the development team.

Addressing flaky tests is not a task that can be put off. It should be a built-in part of the software development strategy. Neglecting this issue increases developer frustration as well as perpetuating the problem itself. Flaky tests tend to multiply over time.

Strategies to combat flaky tests

So, how can software development teams combat the menace of flaky tests? The solution comes from a combination of strategies that prioritize their identification and elimination.

Dedicated resources and time: Allocate dedicated resources and time to tackle flaky tests. This may involve assigning a specific team or individual responsible for identifying, tracking, and resolving flaky tests.

Continuous monitoring: Continuously monitoring test results. By closely monitoring test outcomes, teams will quickly identify which tests are flaky and take action to rectify them.

Root cause analysis: Invest in root cause analysis to determine the underlying reasons for flakiness. Is it a problem with the test itself, the testing environment, or the code being tested? Understanding the root causes is essential for effective mitigation.

Test isolation: Isolate flaky tests to prevent them from affecting the entire testing suite. By containing their impact, developers can continue working on other parts of the codebase without constant interruptions.

Communication and documentation: Foster a culture of communication within the development team. Encourage developers to report flaky tests promptly and document their observations. This collaborative approach can help in faster identification and resolution.

Improving the development process

Taking flaky tests seriously and working to eliminate them can massively improve the software development process by leading to higher software quality and contributing to improved efficiency and productivity.

Efficient development processes attract and retain top talent. Talented developers seek environments where their skills can be put to good use without distraction. 

Alexander Procter

January 16, 2024

3 Min read