What is End-to-End Testing?

End-to-end (E2E) testing is the process of evaluating a SaaS application’s entire operation from beginning to end, ensuring that all integrated components work together smoothly. This is the most basic level in the testing pyramid: According to the very basic guidelines of Google, there should be about 80% of unit tests, 15% of integration tests, and only 5% of end-to-end tests.

This type of testing is important because it shows how the application will be used in the real world, ensuring it meets user expectations at every point of interaction. By simulating real user scenarios, E2E testing catches faults where components connect, which unit tests can miss.

Think of it this way: you’re examining the entire process in a scenario where a user creates an account in your cloud-based application. In this case, an end-to-end test would simulate the entire process: entering information in the registration form, receiving a confirmation email, clicking the activation link, logging in, and accessing the user profile.

However, compared to other testing methods, E2E testing can be more complex. It is more of a time-consuming process to establish and implement. Hence, careful planning is required to be efficient. This is particularly relevant in cloud environments where parameters such as network latency, data security, and data handling scalability are critical.

Running both E2E and unit testing is crucial, as they cover different levels of the testing pyramid, ensuring comprehensive coverage of both individual components and the entire system.

Unit testing verifies the accuracy of individual code units, such as a single function or module. This process entails offering feedback during development and enabling the early identification of bugs.

E2E testing verifies that the application works as expected in real-life situations by testing how the whole system functions from the user’s point of view.

Integrating both testing approaches assists in exposing certain flaws that may not come up when using any of the approaches singularly. For instance, unit tests may not detect integration problems between various modules, while E2E tests may not identify the specific line of code that led to an error.

The right balance between testing methods follows the testing pyramid; Google’s very rough guideline is around 80% unit, 15% integration, and 5% end-to-end tests (Software Engineering at Google, 2020):

• Prioritize Unit Tests: Essentially, we aim to have many fast-moving unit tests for quick identification of errors during the development process.
• Supplement with Integration Tests: Use integration testing to check how different modules or components interact, ensuring their compatibility and functionality.
• Strategically Apply E2E Tests: Run E2E tests only where necessary to capture primary user interactions and verify that the system works correctly in real-life simulations.

The following factors play a key role when finding the balance:

• Complexity: If the application is more complex, then more E2E tests are required.
• Risk: More risky applications require a more extensive level of E2E testing.
• Resources: Be careful not to overload the processes of E2E testing since the time and resources required for creating and maintaining such tests can be significant.

The key difference is scope: E2E testing checks whole user workflows, while unit testing checks single functions or modules.

When you want to write effective end-to-end tests, follow these steps:

• Define your testing goals and scope: Identify the user flows and the functionality that you consider most important for end-to-end testing.
• Identify key user scenarios: Describe the specific steps that a user can take within your application. For instance, in a SaaS business, some important use cases could be viewing products, putting items into a cart, purchasing items, and handling orders.
• Choose the right testing tools and frameworks: Identify efficient tools for your applications and the cloud context in which they will be executed. Some of the important factors that can be considered include the type of technology being used in the application implementation, the technical competence of the team, and the project’s available budget.

Widely used options include:

• Selenium: A popular software tool that allows for the programming of web browsers. The software is cross-platform and supports several programming languages (Selenium).
• Cypress: A JavaScript-based framework that focuses on rapid execution and development capabilities. It’s designed for web applications; its features include time-travel debugging and automatic waiting.
• Playwright: A framework that drives Chromium, Firefox, and WebKit through one API (Playwright).
• Cucumber: This tool focuses on behavior-driven development (BDD) and writing tests in plain language. This allows non-technical parties involved to better understand the evaluation.
• Write your test scripts: Create and maintain understandable and unambiguous test scripts that replicate a user’s actions and contain assertions that check expected results.
• Execute your tests and analyze the results: It is recommended that you run your tests frequently and then analyze the results to determine if there is a problem. E2E tests can be used in regression testing, which re-runs tests after new code is added. Modify the process as needed to maximize test coverage and the accuracy of tests.