There’s a silent problem affecting almost every development team: a test that fails today, passes tomorrow without anyone having touched the code, and fails again the following week. No apparent cause. No clear explanation. Just noise.
This phenomenon has a name: flaky tests , or unstable tests. And while it may seem like a minor inconvenience, its cumulative impact can slow down entire teams, erode confidence in the test suite, and delay critical releases.
In this article we explain what unstable tests are, why they are so difficult to detect, and how tools like BrowserStack allow you to systematically identify and eliminate them.
What is a flaky test?
A flaky test (or unstable test) is an automated test that produces inconsistent results—pass or fail—without any changes to the application’s code. It’s not a bug in the system under test; it’s a flaw in the test itself.
The problem isn’t just technical. It’s organizational: when teams don’t trust their tests, they start ignoring bug alerts. And when alerts are ignored, real bugs go undetected. False positives, ultimately, are just as dangerous as the bugs the suite is supposed to be detecting.
The most common causes of unstable tests
Understanding the root cause of the problem is the first step to solving it. These are the most common causes:
1. Timing issues
The test assumes that an element has already loaded or that an operation has already finished, but in some environments that takes a little longer. The result: it passes locally, but fails in CI. This is the most frequent source of flakiness in user interface (UI) and end-to-end tests.
2. Non-deterministic execution order
Some tests implicitly depend on the state left by the previous test. If the execution order changes—as happens in parallel suites—the test may fail for no apparent reason.
3. Shared resources and career conditions
Tests that share databases, files, or global variables without proper isolation will cause interference. In parallel execution environments, this becomes a constant source of instability.
4. Uncontrolled external dependencies
Third-party APIs, external services, or even the system clock can introduce variability. A test that calls a real API might fail simply because that API experienced a latency spike.
5. Differences between environments
The test passes perfectly on the developer’s machine but fails on the CI server. Different browser versions, operating systems, screen resolutions, or regional settings can unpredictably alter the behavior of a UI test.
The real cost of ignoring flaky tests
Many teams learn to live with unstable tests: they rerun them until they pass and move on. It’s a costly mistake.
Development time lost: Each manual rerun of a failed test consumes team time. Multiplied by dozens of tests and hundreds of runs per month, the impact is significant.
Slower CI/CD pipelines: Automatic re-executions to compensate for instability lengthen build times and slow delivery cycles.
Eroded trust in testing: When teams assume that “that test always fails,” they stop paying attention to it. Eventually, a real bug hides behind what everyone thinks is noise.
Risk of regressions in production: The most serious consequence: bugs that should have been detected by tests reach production because nobody trusts the alerts.
How BrowserStack helps identify and resolve unstable tests
BrowserStack is the world’s leading cloud testing platform, used by QA and development teams at companies of all sizes. Among its most powerful capabilities is Test Observability , a module specifically designed to combat instability in test suites.
Automatic detection of flaky tests
BrowserStack analyzes the execution history of each test and automatically detects those exhibiting unstable behavior. There’s no need for the team to manually review thousands of results: the platform identifies problematic tests, categorizes them, and prioritizes them.
Root cause analysis with artificial intelligence
Once an unstable test is detected, BrowserStack provides detailed contextual information: logs, screenshots, video recordings of the execution, and analysis of recurring errors. This drastically reduces the time needed to diagnose the root cause of the instability.
Execution in real and consistent environments
BrowserStack allows you to run tests on a grid of over 3,500 real-world combinations of browsers, operating systems, and mobile devices. This eliminates the “it works on my machine” variable and ensures that tests are run under reproducible and controlled conditions.
Intelligent re-execution management
The platform allows you to configure selective re-execution policies for tests marked as unstable, without affecting the results of the entire suite. The team gains clear visibility into what is noise and what is a genuine failure.
Native integration with the development ecosystem
BrowserStack integrates directly with leading CI/CD tools (GitHub Actions, Jenkins, CircleCI, GitLab CI), testing frameworks (Selenium, Cypress, Playwright, Appium), and management platforms like Jira. Integration into existing workflows is seamless and requires no major infrastructure changes.
Aufiero Informática: your partner for implementing BrowserStack
Aufiero Informática is an authorized BrowserStack distributor in Latin America. Our team of specialized Sales Engineers can guide you from the initial assessment to the complete implementation of the platform in your organization.
With Aufiero you get:
- Flexible licensing: plans tailored to the size of your team and your testing needs.
- Assisted onboarding: technical support to integrate BrowserStack into your existing pipeline.
- Training: training sessions to help your team make the most of the platform’s capabilities.
- Ongoing support: local technical support in Spanish throughout the entire usage cycle.
Frequently asked questions about unstable tests and BrowserStack
What is the difference between a flaky test and a real bug?
A real bug produces a consistent and reproducible failure: the test always fails under the same conditions because there’s a specific problem in the code. A flaky test, on the other hand, fails intermittently even though the code hasn’t changed. The key difference lies in reproducibility: if you run the same test several times in a row and the results vary, you’re dealing with an unstable test, not a bug in the application.
Do flaky tests only affect UI tests or also unit tests?
They affect all levels of the testing pyramid, although they are more frequent in integration and end-to-end (UI) tests. Unit tests are more deterministic in nature, but they can also become unstable if they depend on external resources, system time, or uncontrolled environment variables.
Does BrowserStack work with the testing framework we already use?
BrowserStack is compatible with the most popular testing frameworks: Selenium, Cypress, Playwright, Appium, Jest, TestNG, PyTest, and many more. It also integrates natively with leading CI/CD platforms such as GitHub Actions, Jenkins, GitLab CI, and CircleCI. In most cases, integration doesn’t require rewriting existing tests.
Is it necessary to migrate the entire testing infrastructure to use BrowserStack?
No. BrowserStack is designed to complement your existing workflow, not replace it. You can start by running some of your tests in the BrowserStack cloud while maintaining the rest of your current infrastructure, and gradually expand its use as your team’s needs grow.
How can I purchase BrowserStack through Aufiero Informática?
You can contact the Aufiero Informática sales team directly through the website. Our Sales Engineers will advise you on the most suitable plan for your team size, manage the licensing, and support you throughout the entire implementation and onboarding process.
Want to delve deeper into the topic? Join our webinar
If this article raised questions for you—or if you recognized some of the symptoms we described in your team—we have a concrete proposal for you.
🎙️ Webinar: No more false positives: how to identify and fix unstable tests
In this live webinar with specialists from BrowserStack and Aufiero Informática , you will learn:
- How to detect unstable tests in your current suite
- Specific techniques for diagnosing and correcting the most common causes of flakiness
- How to use BrowserStack Test Observability to automate detection and analysis
- Best practices for building more reliable and maintainable test suites
📅 Date: April 28 🕐 Time: 5:00 PM ARG | 3:00 PM COL | 2:00 PM MEX 💻 Format: Online — click here to register
