Minimizing flaky test impact

Flaky Tests

Oct 25, 2023

Flaky tests, or those producing inconsistent results, can be a significant thorn in the side of any software development process. They introduce non-determinism into your test suite, often leading to unreliable test results and time-consuming debugging sessions. So how do we mitigate the impact of these failed tests and prevent their recurrence? This tutorial outlines strategies to minimize their impact and enhance the functionality of your test suite.

Minimizing the Impact

Test Retry Mechanisms

One crucial approach is the implementation of test retry mechanisms, an aspect of automated testing that involves rerunning failed tests. The rerun can help determine if the test failure was an isolated occurrence or a consistent issue. This tactic buffers the impact of flaky tests, affording more opportunities for the tests to deliver consistent results, reducing unnecessary debugging, and preventing premature code changes.

Test Environment Isolation

Test environment isolation is also crucial. A common cause of test flakiness is when test cases depend on shared resources or results from previous tests. By creating a self-contained environment for each test, you can eliminate these dependencies, minimizing the likelihood of flaky tests and providing precise feedback on the functionality being tested and the root cause if a test fails.

Timeout Handling

Timeout handling can prevent false failures caused by slow or unresponsive dependencies, another common cause of flakiness. It's especially vital when tests rely on APIs or other external systems that may not always respond predictably. Adjusting timeouts based on each test's specific requirements can reduce flakiness.

Test Frameworks and Automation

The selection of a testing framework and implementation of test automation can substantially influence your test results. A robust testing framework, tailored to your application's specifics (be it JavaScript, HTML, frontend, or end-to-end tests), can mitigate flaky tests' occurrence. By running tests across different configurations, issues involving test order or order dependencies will be immediately obvious. Furthermore, test automation can increase the consistency of test runs, eliminating human error and reducing the chance of introducing flakiness.

Comprehensive Test Reports and Metrics

Comprehensive test reports and metrics tracking provide valuable insights into test flakiness. Detailed reports enable you to understand each test's behavior, pinpointing scenarios under which a test fails. By tracking metrics over time, patterns and trends related to test flakiness become apparent, enabling a focused approach to the most problematic areas.

Case Study: Slack’s Approach to Flaky Tests

In 2019, Slack undertook a significant effort to resolve flaky tests issues. After spending some time in identifying flaky tests, they established flakiness thresholds - if test flakiness exceeded that threshold, it would be automatically disabled. The results of this automation has tremendous impact on product stability, engineering velocity, and test confidence.

They saw a dramatic improvement in their main branch stability, increasing from 19.82% in July 2020 to 96% in February 2021. Similarly, the rate of test job failures plummeted from 56.76% to 3.85% over the same period. These enhancements boosted developer sentiment and confidence considerably.

Moreover, the automation of test triaging saved substantial developer time. In detail, it created 693 PRs for Android and 492 PRs for iOS, resulting in an overall saving of 553 hours (equivalent to 23 full days of developer time).

Feedback from developers further attested to the project's success. One developer stated, "I feel iOS CI is much more stable and fast than before. Thank you for all the hard work! It improves our productivity by far. Really appreciated!” Moreover, survey results showed that 74% of developers felt the project had positively impacted main branch stability, and 64% reported reduced reruns on PR.

Read more about the study here.

Test Detection and Reporting: Tools and Collaboration

The use of sophisticated tools and fostering collaboration within development and DevOps teams can significantly enhance the process of preventing, identifying, and reducing flaky tests.

BuildPulse offers a comprehensive platform to find and flaky tests, measure their impact on the engineering team, and alert stakeholders of any issues while they’re still manageable. We go beyond reporting and give you tools take action, such as automated test quarantining, to handle the problem end-to-end.

FAQ

Does BuildPulse replace my current CI system?

No.

We use GitHub Actions / CircleCI / Semaphore CI self-hosted functionality to run your builds on our infrastructure.

Other than faster builds, there are no changes to your developers' workflows - you can continue using your CI system as-is.

How is BuildPulse faster than GitHub Actions hosted runners?

We use GitHub’s self-hosted functionality to run your builds on our infrastructure with latest generation + high single-core performance CPUs, also then further optimized for CI-type workloads. We’ve also tuned our VMs and block storage devices, increasing baseline performance while also cutting costs in half.

We also provide a toolkit to further speed up your pipelines, which includes ultra fast remote docker builders, docker layer caching, dependency caching, and more. With all of these improvements, we’ve seen 2x+ performance improvements in build times.

Can I use BuildPulse with other CI providers than GitHub Actions?

Yes! BuildPulse Runners will run jobs for CircleCI, SemaphoreCI - GitLab coming soon.

We aim to support all popular CI systems. If you're using one that's not listed, please contact support@buildpulse.io!

Is there a free trial available?

Yes, you can book a meeting here!

How do you secure my builds?

BuildPulse runs each job in a network- and compute- isolated environment with ephemeral VMs that leave behind a clean state after every run.

Do you support Mac and Windows runners?

This is on our roadmap! Email us at hello@buildpulse.io, or book a demo here!

Is BuildPulse SOC 2 compliant?

Yes, BuildPulse is SOC 2 Type 2 compliant.

Contact us at hello@buildpulse.io for more information.

How are BuildPulse Runners priced?

BuildPulse Runners charges on a per-second basis, which depend on the runner-type used. See our pricing page for more details.

How long does implementation/integration with BuildPulse take?

The minimum implementation involves 2 steps: Signing up for BuildPulse, and changing 1 in your GitHub Actions yaml file.

If you're using Semaphore CI or Circle CI, it's a 4 line change. See our Getting Started guide for more details.

Does BuildPulse replace my current CI system?

No.

We use GitHub Actions / CircleCI / Semaphore CI self-hosted functionality to run your builds on our infrastructure.

Other than faster builds, there are no changes to your developers' workflows - you can continue using your CI system as-is.

How is BuildPulse faster than GitHub Actions hosted runners?

We use GitHub’s self-hosted functionality to run your builds on our infrastructure with latest generation + high single-core performance CPUs, also then further optimized for CI-type workloads. We’ve also tuned our VMs and block storage devices, increasing baseline performance while also cutting costs in half.

We also provide a toolkit to further speed up your pipelines, which includes ultra fast remote docker builders, docker layer caching, dependency caching, and more. With all of these improvements, we’ve seen 2x+ performance improvements in build times.

Can I use BuildPulse with other CI providers than GitHub Actions?

Yes! BuildPulse Runners will run jobs for CircleCI, SemaphoreCI - GitLab coming soon.

We aim to support all popular CI systems. If you're using one that's not listed, please contact support@buildpulse.io!

Is there a free trial available?

Yes, you can book a meeting here!

How do you secure my builds?

BuildPulse runs each job in a network- and compute- isolated environment with ephemeral VMs that leave behind a clean state after every run.

Do you support Mac and Windows runners?

This is on our roadmap! Email us at hello@buildpulse.io, or book a demo here!

Is BuildPulse SOC 2 compliant?

Yes, BuildPulse is SOC 2 Type 2 compliant.

Contact us at hello@buildpulse.io for more information.

How are BuildPulse Runners priced?

BuildPulse Runners charges on a per-second basis, which depend on the runner-type used. See our pricing page for more details.

How long does implementation/integration with BuildPulse take?

The minimum implementation involves 2 steps: Signing up for BuildPulse, and changing 1 in your GitHub Actions yaml file.

If you're using Semaphore CI or Circle CI, it's a 4 line change. See our Getting Started guide for more details.

Does BuildPulse replace my current CI system?

No.

We use GitHub Actions / CircleCI / Semaphore CI self-hosted functionality to run your builds on our infrastructure.

Other than faster builds, there are no changes to your developers' workflows - you can continue using your CI system as-is.

How is BuildPulse faster than GitHub Actions hosted runners?

We use GitHub’s self-hosted functionality to run your builds on our infrastructure with latest generation + high single-core performance CPUs, also then further optimized for CI-type workloads. We’ve also tuned our VMs and block storage devices, increasing baseline performance while also cutting costs in half.

We also provide a toolkit to further speed up your pipelines, which includes ultra fast remote docker builders, docker layer caching, dependency caching, and more. With all of these improvements, we’ve seen 2x+ performance improvements in build times.

Can I use BuildPulse with other CI providers than GitHub Actions?

Yes! BuildPulse Runners will run jobs for CircleCI, SemaphoreCI - GitLab coming soon.

We aim to support all popular CI systems. If you're using one that's not listed, please contact support@buildpulse.io!

Is there a free trial available?

Yes, you can book a meeting here!

How do you secure my builds?

BuildPulse runs each job in a network- and compute- isolated environment with ephemeral VMs that leave behind a clean state after every run.

Do you support Mac and Windows runners?

This is on our roadmap! Email us at hello@buildpulse.io, or book a demo here!

Is BuildPulse SOC 2 compliant?

Yes, BuildPulse is SOC 2 Type 2 compliant.

Contact us at hello@buildpulse.io for more information.

How are BuildPulse Runners priced?

BuildPulse Runners charges on a per-second basis, which depend on the runner-type used. See our pricing page for more details.

How long does implementation/integration with BuildPulse take?

The minimum implementation involves 2 steps: Signing up for BuildPulse, and changing 1 in your GitHub Actions yaml file.

If you're using Semaphore CI or Circle CI, it's a 4 line change. See our Getting Started guide for more details.

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