Test Flakiness: What It Is, Causes, and Solutions

Unreliability in tests can be a nightmare situation for testers. No matter how experienced the testing team is, test flakiness can trouble the heck out of them. It is a hell you should avoid at all costs. But if you ever get sucked into the tornado of flaky tests, knowing how to come out of it is essential. If you have been in the testing field for a while, it is clear that flaky tests don’t offer any value.

They are the most common type of hurdles during mobile app test automation. Every time a testing team performs automated testing, dealing with flaky tests tends to slow down the entire Software Development Life Cycle. Therefore, it is vital to have a comprehensive picture of what test flakiness is, what causes it, and how to deal with flaky tests. Let us take a detailed look.

What are Flaky Tests?

If a test sometimes passes or fails without any valid reason during test automation, it is a flaky test. These tests might work fine for some time but abruptly begin to fail later. This phenomenon sometimes prompts testers to chalk these tests up as a system glitch that leads to ignoring the test result that has already failed.

Other times, a particular test can continue with an inconsistent performance which can encourage the tester to stop running it altogether. It drastically reduces test coverage and can lead to unnoticed failed test results.

You can miss bugs, whether it is a lower test coverage or ignoring failed tests. The changes are also easy to overlook between failing and passing test runs. But it is important to note that a change caused the test result failure.

What Causes Test Flakiness?

The first step toward dealing with test flakiness is to determine its causes. Here they are.

1.    Data Management Issues

Running multiple tests with the same account can cause collisions, especially with Appium automation testing. For instance, since one test already uses the account, another might result in a log-in failure.

2.    Non-Determinism

Sometimes, application behavior can show non-determinism, leading to test flakiness. It is a feature that displays erratic behaviors or results despite the same input between runs.

3.    Problems In The Test Environment

Issues in the test environment are one of the leading causes of test flakiness. For example, an application loads very slowly. It can intermittently go offline or crash, run slower than usual, display network latency, or execute action before a page finishes loading.

4.    Compromised Internet Connection Speed

If the traffic load increases on a line, the speed of the internet connection becomes slower and can compromise the visibility of page elements. It causes the test to fail at that particular instant even if it passes when the internet connection speed resumes.

5.    Dynamic elements and application DOM

The value of the attributes of dynamic elements changes when you reload the web page. If a test doesn’t cater to dynamic elements, it can return a fail. Similarly, significant changes to the application DOM reflects UI change. It can result in test flakiness in case of an update to the DOM structure, style, or content.

How You Can Deal With Flaky Tests

Since we have already established that a complete escape from test flakiness is not possible, you should give your best to avoid or at least reduce flaky tests. If they still occur, it is crucial to deal with them before they cause further damage. Let us check out this section in detail.

1.    Isolating Tests

When you are in the planning phase of your test structure, isolating test cases ensures the independent running of your tests. This improves test performance and prevents any leftover data or side effects from other tests from causing hurdles in your way.

2.    Optimization of The Test Structure

Begin with small tests and keep them simple by avoiding the overloading of logic. As a result, your test structure will be more stable and will play a crucial role in preventing test flakiness.

3.    No Fixed Waiting Times

If you are looking forward to avoiding or reducing flaky tests for the long haul, never rely on fixed waiting times. Adopt dynamic waiting times instead. If you end up choosing a longer waiting time, the test suit will slow down. Worse, if you don’t wait for enough, the test will fail since it won’t proceed due to the lack of readiness of the application under the test.

4.    Separate Test Design and Test Data

Separating test design and test data facilitates the running of data sets via tests is a wise move. It enables you to perform parallel testing to fasten the pace of development and product delivery. Limiting dependency between different tests prevents overall failure. Therefore, you can easily figure out where the problems are arising.

5.    Reducing Environmental Dependency

You can start out by limiting external system calls, parametrizing connections, and building mocking servers. Having too much dependency on the environment can backfire as they don’t 100% mimic real-world scenarios. It is not feasible to cut all dependencies. But reducing them is one of the best practices you can undertake to minimize test flakiness.

Conclusion

We are facing an explosion of different varieties of browsers, mobile phones, IoT devices, and so on. It has raised the demand for building easy-to-maintain and scalable automated tests and has simultaneously given rise to roadblocks on the way. Testers already realize that even the slightest changes in the code base or user interface can cause random flaking of automated tests.

Test flakiness also increases maintenance overhead duration and slows down feedback loops. As a result, the entire testing cycle gets hindered. No testing team in this world has ever encountered zero test flakiness. Most Quality Assurance teams just brush It under the rug. They keep doing it until the rug becomes bumpy, and it is impossible to ignore flaky tests anymore!

Testing teams should never forget that you can achieve positive test results with high pass rates by reducing test flakiness even by one-tenth. You might have heard that it’s impossible to eliminate flaky tests. But it is possible to reduce their occurrence. Every bit counts if you aim for a more streamlined and highly accurate testing cycle.