Stop Running High-Risk E2E Tests in Every Browser

Here’s a Smarter Approach

Introduction

Cross-browser testing ensures your web application works consistently across different environments, but not all tests belong in your cross-browser suite. A common mistake? Running high-risk, end-to-end (E2E) journey tests across multiple browsers. This leads to flaky results, slow feedback loops, and unnecessary maintenance headaches — without adding much value.

Instead, cross-browser testing should focus on compatibility validation, not user flows. In this article, we’ll break down the difference between compatibility testing vs. user flow testing and show you how to streamline your test strategy for faster, more reliable cross-browser validation.

The Difference Between Compatibility Testing and User Flow Testing

It’s crucial to distinguish between compatibility testing and user flow testing, as they serve different purposes:

• Compatibility Testing ensures that an application’s core components — such as rendering, JavaScript execution, and API interactions — work consistently across different browsers and environments. It focuses on identifying browser-specific issues like CSS inconsistencies, unsupported JavaScript features, and differences in Web API behaviors.
• User Flow Testing, on the other hand, validates end-to-end journeys, ensuring that users can complete key workflows successfully. This type of testing evaluates interactions, such as form submissions, navigation, and business logic execution, to confirm that all components function together as intended.

While user flow testing is essential for assessing overall application behavior, it is not well-suited for cross-browser testing due to the increased risk of false positives and flaky tests. Compatibility testing should be the primary focus when verifying functionality across multiple browsers.

The Problem with High-Risk Journey Tests in Cross-Browser Testing

Many teams assume that if a test is important, it should run on every browser. However, this mindset ignores the fundamental purpose of cross-browser testing. Running complex, multi-step user journey tests across different browsers introduces several issues:

1. Increased Flakiness and False Positives

High-risk E2E tests typically involve:

• Multiple UI interactions across different pages
• API calls with dynamic responses
• Dependency on external systems (databases, third-party integrations, etc.)

Differences in browser execution timings, animations, and resource loading can cause these tests to fail intermittently even when the core functionality is intact. This leads to false positives, requiring engineers to spend time debugging browser-specific quirks that may not impact real users.

2. Slower Feedback Loops

E2E tests are inherently slower than unit or integration tests. Running them across multiple browsers further amplifies test execution time, delaying feedback and slowing down deployments. A smarter approach is prioritizing critical compatibility checks over redundant, full-fledged E2E runs.

3. Unnecessary Maintenance Overhead

Every additional browser in the test matrix increases maintenance costs. High-risk journey tests often require frequent updates due to:

• UI layout changes
• New browser versions with minor rendering differences
• Variations in JavaScript execution timing

Maintaining these tests across multiple browsers results in constant firefighting rather than meaningful validation.

A Better Approach: Isolate Core Rendering and Execution Paths

To make cross-browser testing efficient and reliable, shift the focus toward isolating core rendering and execution paths rather than verifying complete user journeys. Here’s how:

1. Focus on Rendering and JavaScript Execution

Instead of running full E2E tests, validate core browser-dependent functionality:

• CSS and layout rendering differences
• JavaScript execution inconsistencies (e.g., ES6 features, event handling)
• Web API support (e.g., IndexedDB, WebSockets, Service Workers)

2. Use Component-Level and Visual Testing

Adopt visual regression testing tools (like Applitools or Percy) to catch UI inconsistencies efficiently without running full journey tests. This helps pinpoint styling issues without unnecessary complexity.

3. Prioritize Business-Critical Browsers

Instead of testing all browsers equally, prioritize based on:

• User analytics data (focus on browsers that drive conversions)
• Rendering engine coverage (e.g., testing Blink covers Chrome, Edge, and Opera)
• Known browser quirks (older versions of Safari may need special handling)

4. Run High-Risk Journey Tests in a Single Primary Browser

For critical workflows, execute E2E journey tests on a single stable, widely-used browser (e.g., latest Chrome or Firefox). Then, use targeted cross-browser tests for compatibility validation.

Conclusion: Smarter Cross-Browser Testing

Cross-browser testing should not be about re-running the entire test suite across multiple browsers. Instead, it should focus on: 1) Validating rendering and execution consistency; 2) Using visual and component-based testing; 3) Prioritizing business-critical browsers; 4) Running high-risk journeys only where necessary

By refining your test strategy, you can reduce flakiness, speed up execution, and ensure reliable cross-browser compatibility without unnecessary overhead.

Are you still running full E2E tests in all browsers? It’s time to rethink your approach!

𝓗𝒶𝓅𝓅𝓎 𝓉𝓮𝓈𝓉𝒾𝓃𝓰 𝒶𝓃𝒹 𝒹𝓮𝒷𝓊𝓰𝓰𝒾𝓃𝓰!

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Stop Running High-Risk E2E Tests in Every Browser was originally published in Women in Technology on Medium, where people are continuing the conversation by highlighting and responding to this story.