A Comprehensive Guide to E2E Testing

Welcome to the wild world of end to end (E2E) testing, where we put ourselves in the user’s shoes and examine an app from their perspective.

Your mission? To ensure every piece of the application works together seamlessly “in the wild” — meaning in real-world scenarios across different platforms and user behaviors.

So gear up as we trek through the treacherous terrain of E2E testing, uncovering why it’s important and how you can master it to create robust, user-friendly applications.

What is E2E testing?

Imagine you’ve built a complex machine with countless moving parts. Naturally, you’d want to ensure that when you press the “ON” button, it performs its every intended function flawlessly from start to finish.

This is what end to end software testing aims to achieve for software applications.

The E2E testing process analyzes app functionality from a user’s first contact with the app to the moment they close it. The goal is to validate an app’s functionality and performance by simulating real-world usage scenarios.

Types of E2E testing: Horizontal vs vertical

There are two main flavors of E2E testing — horizontal and vertical — each with their own special sauce:

Horizontal E2E testing: The user’s perspective

Horizontal E2E testing simulates the user experience from start to finish. It targets the front end — how things look, feel, and perform from the user’s point of view across different operating systems, browsers, and devices, including:

• Verifying user interface elements and interactions
• Checking navigation flows and menu functionality
• Ensuring data input and output are correct from the user’s perspective
• Testing responsiveness across different devices and screen sizes

Vertical E2E testing: Diving into the technical depths

Vertical E2E testing focuses on the back-end functionality, ensuring all connections work, data flows correctly, and processes run between app layers without exceptions, including:

• Verifying database operations and data integrity
• Testing API integrations and microservices communication
• Checking background processes and scheduled tasks
• Ensuring proper error handling and logging

The importance of E2E testing: Because users are unpredictable

Let’s face it — users will always find ways to use your app that you never imagined.

E2E testing helps catch unpredictable “Why is the user doing that?!” moments before they become “Why is our app broken?!” situations. It’s particularly useful for capturing issues like:

• Cross-component failures: issues arising from component interactions, such as conflicts between user profile updates and notification systems
• Load-induced bottlenecks: performance problems that surface under realistic user loads, like an e-commerce site crashing during a sale
• Edge-case scenarios: critical bugs in unusual user journeys, such as a banking app glitching during specific fund transfer scenarios
• User flow inconsistencies: issues where the application behaves unexpectedly, causing users to encounter infinite loops or dead-end pages (we’ve all been there)
• Data integrity issues: data consistency and accuracy problems, e.g. when a confirmation message displays data that is different from what a user expects

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Step-by-step guide to performing E2E testing

Implementing E2E testing isn’t a push-button process — it involves planning, execution, and analysis. We can break it down into four stages:

Test planning

Once you’ve confirmed that your app’s modules can actually talk to each other (integration testing), it’s time to outline your E2E test objectives:

• Analyzing your client’s requirements and the app’s architecture
• Identifying critical user flows and functionalities
• Defining test scope and any particular objectives (often focused on fixing or investigating issues flagged in earlier tests)
• Allocating resources and setting timelines

Test design

This is where the rubber meets the road. You’ll create your test environments, build the actual tests, and conduct risk and usage analysis:

• Creating detailed test cases based on user behaviors
• Setting up test environments that mimic the real world
• Selecting appropriate testing tools and frameworks
• Defining test data requirements

Execution

The “let’s break stuff” phase. It’s time to run the tests. This involves:

• Running automated E2E tests across different environments
• Performing manual tests for scenarios that are difficult to automate
• Monitoring test execution and logging results
• Identifying and categorizing any issues or failures

Results analysis

The postmortem, where you figure out what went wrong, why it went wrong, and how to fix it, including:

• Analyzing test results and identifying patterns
• Prioritizing issues based on severity and impact
• Carrying out root-cause analysis of failures
• Collaborating with developers to fix identified issues

Key benefits of E2E testing — it’s worth the headache

E2E testing isn’t just another checkbox on your QA to-do list — it’s a potent tool for creating software that people actually enjoy and don’t write bad reviews about. Here’s why it’s worth its weight in gold:

1. User centric through and through: Unlike other testing methods that focus primarily on the app itself, E2E testing centers on the user’s experience. It ensures that the app works smoothly and meets user and client requirements.
2. Early bug detection: By spotting issues during the development cycle rather than after launch, E2E testing allows you to fix problems before users find them.
3. Improved app reliability: E2E testing makes apps more dependable by covering a wider range of scenarios than unit and integration tests, resulting in a more robust testing methodology.
4. Increased test coverage: Compared to methods like integration testing, E2E testing is more holistic, assessing overall app functionality and not just that of individual components or connections.

Three key challenges in E2E software testing

E2E testing isn’t all smooth sailing, which you might attest to if you’ve tried it before! Here are three hurdles you’ll need to jump:

1. It’s time consuming: Creating testing suites and monitoring environments can be lengthy. Running thousands of tests takes time, though end to end testing automation tools can help streamline the process.
2. Environment setup complexity: Even the best tests won’t yield accurate results without proper environment configuration. Having the right agents installed locally and remotely is crucial, and without the proper tools you’ll struggle to run quality tests.
3. Understanding user goals: E2E testing requires a shift in focus from features to solutions. You need to look beyond features and instead consider how effectively they solve user problems in real-world scenarios.

Best practices for end to end testing

Determined to master E2E testing? Great — a brave new world awaits you! — but keep these best practices in mind:

1. Prioritize critical workflows: First, focus on the app’s most crucial elements, including frequently used features, complex connections, and workflows.
2. Avoid exception testing: While focusing on errors is tempting, the E2E testing stage isn’t the right time for extensive exception testing. Understanding root causes and impacts is more valuable than simply finding errors.
3. Reduce UI glitches: UI tests are vital as they directly impact user experience. Focus on tests that account for the inherent unpredictability of user interactions and use testing tools that allow for some variability in results.
4. Embrace automation: You’ll likely have thousands of tests to run, so automation is essential. Invest in the right tools to automate your E2E testing process at scale.

End to end testing vs integration testing

While E2E testing and integration testing are both critical to the software testing process, they have distinct characteristics.

E2E testing explores app behavior from the user’s perspective. Conversely, integration testing focuses on verifying the interactions between different components or modules of a system to ensure they work together correctly.

It’s a bit like this: While integration testing is like checking if all the LEGO pieces fit together, E2E testing is building the entire LEGO Death Star and making sure it can (metaphorically) destroy planets.

Here’s a comparison table to break down the key differences:

E2E testing demands the best tools in the business, which Incredibuild delivers

E2E testing is the final gauntlet before your app confronts the chaos of the real world — an opportunity you must use wisely!

Remember, this is not just about finding bugs — it’s about ensuring your application delivers the experience and functionality your users expect.

One thing you’ll probably find is that even when you master the art of E2E testing, long test runs might eat into your development time, especially if you’re dealing with limited compute power.

This is where tools like Incredibuild can step in to speed up your testing process without sacrificing quality. Incredibuild accelerates computationally intensive software development tasks — a perfect fit for high-quality E2E testing at scale. Here’s what it brings to the E2E testing table:

1. Accelerated testing: Incredibuild vastly reduces the time it takes to run your E2E test suites. Run more tests in less time, allowing for more frequent and thorough testing cycles.
2. Resource optimization: Incredibuild efficiently allocates computing resources, giving you extra power when you need it without requiring massive infrastructure investments.
3. Seamless integration: Incredibuild seamlessly integrates with popular development tools and CI/CD pipelines, and slots right into your testing workflows.
4. Scalability: Whether you’re a small team or a large enterprise, Incredibuild scales to meet your needs and adapt to your project’s growing complexity.

With Incredibuild, you can identify issues earlier, iterate faster, and ultimately deliver higher-quality software to your users.

Don’t let slow E2E testing hold back your development speed or software quality — book a demo with Incredibuild and level up your test workflows today.

E2E testing FAQs

Q: What is UAT, and how does it differ from E2E testing?

User acceptance testing (UAT) involves actual end users testing the app to ensure it meets their needs and expectations. E2E testing is typically performed by the development team, while UAT is conducted by or with the client or end users.

Q: What is the difference between E2E testing and regression testing?

E2E testing checks the entire application flow, while regression testing ensures new changes haven’t broken existing functionality. Regression testing is often defined as a subset of E2E testing, focused on verifying that recent changes haven’t negatively impacted existing features.

Q: Can you provide an end to end testing example?

An e-commerce site is a good example of how end to end testing can be used in software testing. You’d test the entire process of logging in, searching for a product, adding it to the cart, applying a discount code, checking out, receiving an order confirmation email, and then verifying the order in the admin panel.

This scenario tests multiple interconnected systems (user authentication, product catalog, shopping cart, payment processing, email services, and admin interfaces) in a single flow, just as a real user would experience.

As we can see, E2E testing is all about putting yourself in the user’s shoes and ensuring that every step of their journey through your application is smooth and error free.