A Complete End to End (E2E) Testing Tutorial: Comprehensive Guide With Examples and Best Practices

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  • A Complete End to End (E2E) Testing Tutorial: Comprehensive Guide With Examples and Best Practices

OVERVIEW

End to end testing or E2E testing, as the name itself suggests, is the testing methodology that validates a software workflow from starting to end. The primary goal of E2E testing is to simulate an end user's application journey and ensure that all integrated components, dependencies, and other integrated pieces work as per expectations.

While this looks really obvious, that the testing has to be done with all components attached, in practicality, end to end testing is the last stage of testing and usually not done very frequently. This is especially so if the application under test is big, i.e. have hundreds of components and thousands of dependencies.

End to end testing is time consuming, requires more infrastructure than unit and integration testing, and it is relatively difficult to pinpoint exact breakage with this methodology. Yet as it covers the most accurate end user scenarios, it is also the most significant testing process as well.

In this post. We'll explain end to end testing, along with how it fits into a larger testing strategy that can be advantageous to any firm. We will focus on what exactly end to end testing is, how it differs from unit and integration testing, why it’s an important part of overall quality assurance, and how LambdaTest End to End testing cloud makes your E2E testing faster and more efficient.

What is End to End Testing?

End to end testing involves testing all aspects of an application right from start to finish. It aims to ensure that an application's flow works or behaves as expected. By simulating a real-world scenario as close as possible to what real end users do, E2E testing helps you improve your team's software.

This execution of complete user workflows is more comprehensive than unit testing or integration testing methodologies. Usually, it involves executing the program along with all possible dependencies, including the database, outside services, metrics, logging, etc. Again to reiterate, the aim is to be as close as possible to real-world scenarios.

Therefore, in ideal E2E tests, all components and dependencies are usually validated rather than just a selected set of features like in Integration testing. End to End testing can be done both manually or via automation scripts.

Check out our Complete Guide to End to End Testing with examples to learn more!

Testing Pyramid

Testing Pyramid is a software development framework that can foster high-quality code by minimizing the time required for developers to determine if changes affect the existing code. It also aids in developing a more robust test suite.

The testing pyramid is a model that provides a structure for the types of tests to be performed in automated test suites. It also defines the order and frequency of such assessments. The purpose is to provide rapid feedback to ensure that code changes do not impact existing functionality.

Testing Pyramid

Test automation pyramid consists of three levels:

  • Unit Tests
  • Integration Tests
  • End to end Tests

Unit Tests:

Unit tests serve as the foundation of the test pyramid. Tests have a limited scope and ensure that isolated code units function as expected without depending on external dependencies. The team executes pre- and post-commit tests in this pyramid layer, which are developer triggered.

Integration Tests:

Integration tests are a crucial part of software testing. Unit tests check small portions of a codebase, while integration tests ensure that the software communicates efficiently and retrieves accurate data to perform as expected. Integration tests ensures that your software interacts with external components, such as APIs and databases. Integration tests can ensure that data is retrieved on time and that your software communicates efficiently with these external components.

Integration tests are slower and more complex than unit tests because they require interaction with external sources. They also need a pre-production environment to run. Having the right balance of virtual and real devices is critical for running integration tests.

End to End Testing:

End to end testing checks all of the code that was written for an application and is the most expensive to maintain. It uses a test environment and data to simulate real-world functionality and has the slowest operating pace. Because it checks assembled applications, it is also the most difficult to identify issues with.

End to end tests are the most expansive form of automated testing and can be the most time-consuming part of a testing cycle. They often have unreliable external dependencies like integration tests and can take a long time to set up and run.

Why is E2E Testing Important?

All modern applications are built using lots of moving parts. An enterprise grade application has hundreds of components and thousands of dependencies, all of which are deployed on an ecosystem of infrastructure layer which is itself composed of multiple parts working together. All this complexity creates massive avenues of unpredictable failures. A single isolated system could be working smoothly and perfectly. However a collection of such systems may create conflicts with each other and create issues.

Therefore for ensuring final quality assurance of all moving parts, it is important to simulate how the end user will interact with the final application that is composed of all components and dependencies. This calls for the need of running end to end testing of all workflows ranging from easy simple steps to complex workflow scenarios.

End to end tests rely on user behaviour, which can be seen during usability testing and recorded in tickets. Before delivering the product to end-users, end to end tests make it easier to find issues. End to end tests assist managers in setting priorities for activities in the development backlog by determining the significance of a process to users in real life.

End to end testing can also enhance the user experience. User expectations form the basis for test cases, particularly for applications that require a lot of user engagement, like web and desktop apps.

End to end testing is prevalent since it:

  • Enables release teams to automate crucial user pathways, reducing the time to market.
  • Decreases the time needed to test software, lowering the overall cost of producing and maintaining software.
  • Runs the test cases depending on the end user's behavior to ensure the application functions properly.
  • Aids in reliably and predictably detecting issues.
  • Adds more specific test cases than other testing techniques like unit and functional testing, which helps teams increase their test coverage.
  • End to end tests are the best indicator of application health.
  • Writing end to end testing test cases is relatively simple and intuitive as it mimics real world scenarios. It’s also easier for a tester to start writing E2E tests as it’s easier to write black box E2E tests.
  • End to End testing has a broader range of test case coverage and you can easily expand coverage of new components by adding steps in test scenarios.

Each software is connected to and integrated with a variety of outside databases and systems. It should go without saying that this makes the app's workflow more complex. E2E testing verifies that all of an application's many dependencies are operating correctly. It also checks to see if precise data is being communicated between different system components.

  • Backend: E2E testing looks at an app's backend code and database. Backend functionality is necessary since it is essential to the program's primary functions.
  • Multi-tier Architecture: When an application has a complex architecture with a multi-tier workflow, E2E testing is necessary to verify the system's overall operation and the interactions between its many levels.
  • Distributed Environment: Applications created in cloud or SOA (service-oriented architecture) environments must undergo E2E testing. Furthermore, multi-part apps must work smoothly for them to function.
  • Consistent User Experience: Because E2E testing covers the front, it also ensures that the app's user experience is adaptable to various hardware, software, and environment configurations. Cross-browser testing, for instance, is essential.

End to End Testing Lifecycle

End to End Testing Life Cycle

An end to end testing lifecycle consists of test planning, test design, test execution, and test results analysis.

  • Test Preparation: This phase outlines the primary duties, timetable, and resources involved.
  • Test Plan: The second phase consists of the creation of test specifications, test cases, usage and risk analysis, and the scheduling of tests
  • Testing: Carries out test scenarios and records testing outcomes.
  • Results Analysis: In the final phase, Because E2E testing covers the front, it also ensures that the app's user experience is adaptable to various hardware, software, and environment configurations. Cross-browser testing, for instance, is essential.

Process of End to End Testing

End to end testing involves mainly the following tasks:

  • Examination of end to end testing requirements.
  • There are descriptions of each system's roles and duties.
  • Techniques and standards for testing.
  • Configuration of hardware and software for the test environment.
  • Describe each system and any related processes.
  • Data on each system's inputs and outputs.
  • Fully developed test case design and requirements tracking.

Creating End to End Test Cases

End to-end Testing Design framework is comprised of three parts:-

  • Build user functions
  • Build Conditions
  • Build Test Cases

Here is the detailed view:-

Build User Functions

The actions listed below must be carried out as part of the build user functions:

  • List the system's features and the ways they are connected.
  • List the input, action, and output data for each feature or function.
  • Determine the connections between the functions.
  • Ascertain whether the function is standalone or reusable.

For instance, if you logged into your bank account and transferred money to a third-party account at another bank.

Build Conditions Based on User Function

The following tasks are considered as part of the build conditions:

  • Establishing a set of requirements for every user function specified.
  • Sequence, timing and data conditions are examples of conditions.

For example -Checking of more conditions like:

Login Page

  • Invalid username and/or password.
  • Check your username and password.
  • Checking password strength.
  • Checking of error messages.

Balance Amount

  • Check if the transfer has been completed within 24 hours.
  • If you do not have enough money in your account to complete the transfer, the transaction will fail.

Build a Test Scenario

We will construct a test scenario for the specified user function:

In this instance,

  • Enter the system.
  • Verify your bank balance.
  • Transfer your bank balance.

Key Benefits of End to End Testing

Some of the key benefits of end to end testing that can help you on your testing journey are listed below:

  1. Ensuring Correctness and Health of the Application:

    End to end testing validates an application at all layers – data, business rules, integration, and presentation. Doing so helps ensure the application's correctness and health.

  2. Increases Confidence:

    End to end testing not only ensures that the application functions correctly but also increases confidence in its performance because it is tested across multiple devices and platforms.

  3. Reduces Risks:

    The end to end testing process allows for a rigorous testing of the application at the end of each sprint and iteration, which reduces the risk of failure in the future.

  4. Less Repetitive Efforts:

    End to end testing allows for more thorough testing, which reduces the chances of frequent breakdowns and ultimately reduces repetitive testing efforts.

  5. Reduces Cost and Time:

    By automating your end to end tests, you can reduce the number of times you need to test an application, which in turn reduces the amount of time and money it takes to maintain and improve that application.

Check out our detailed Protractor tutorial to learn how you can perform End to end Testing for AngularJS.

Challenges with End to End Testing

End to end testing has several advantages but also some disadvantages as a method of software testing. End to end testing presents difficulties because:

Test Falkiness:

The end to end testing approach has earned a reputation for flaky tests that fail unexpectedly. Frustratingly, this means that your test suite can pass one day, even though it’s broken, and then fail the next day for no reason.

Because end to end tests have so many moving parts, it’s hard to figure out what’s causing a problem. This inconsistency leads to lost productivity when diagnosing the root cause of flakiness since it’s nearly impossible to replicate failing scenarios. As a result, teams end up accepting flaky tests and ignoring potential issues.

Slow Test Execution:

In addition to the flakiness issues mentioned above, end to end tests take too long to run. While it’s unfair to compare the speed of these tests to unit or functional tests, which are much faster and only test a portion of your application, slow tests hinder developer productivity and cause unnecessary frustration.

Slow test suites can hamper the ability of software development and testing teams to work efficiently. For instance, many teams nowadays rely on successful test runs in their continuous integration system before merging code modifications or deploying new features.

High Maintenance:

End to end tests are longer than other tests because they cover longer flows and have more steps and assertions. For example, when testing an e-commerce website, an end to end test might go through searching for a product, viewing its details page, adding it to a cart, and finalizing the order. These actions represent a wide range of functionality within the application, making the test extensive.

As your end to end test suite grows, it becomes harder and harder to add new tests without interfering with existing ones. Over time, minor changes to the application can bring down your entire test suite. That’s why you should plan your end to end tests with long-term maintenance in mind.

Gathering Actionable Items:

You’ll notice the benefits of test automation once you have a few end to end tests working. Your team will have more time to focus on other high-value work, and you’ll likely notice a few spots to improve in the underlying application. While test automation can provide some peace of mind, your team still needs to address any potential issues that stem from its usage.

When an application's automated end to end tests are integrated into the development workflow, they can help teams more readily identify when changes break existing functionality. Not only do robust test suites help to alert a team when something violates, but they can also be used to verify new features are contributing to the application's overall success.

Demonstrating Values:

Automating end to end tests takes time and effort for any project. While there have been advances in testing tools, there’s still a non-trivial amount of work required to create an automated test suite. The key is to plan your testing strategy, prioritize resources and find time to get started.

Because it can be difficult to immediately demonstrate the usefulness of end to end testing at the start of a project, teams can abandon their efforts too quickly without anything to show for them.

E2E Testing Example

Let's imagine that testers need to confirm that a Gmail account is operational. The following attributes need to be examined:

  • To open the Gmail login page, enter the URL into the address box.
  • Enter your account using legitimate credentials.
  • Access Inbox. Examine your read and unread emails.
  • Create a fresh email.
  • Respond to and forwarded an email.
  • Dispatch the Sent Items folder. Verify your emails there.
  • Go to the Spam folder. Verify your emails there.
  • To exit Gmail, click the "logout" button.

Perform end to end Testing flawlessly. Try LambdaTest Now!

Types of End to End Tests

E2E testing is divided into two categories:

  • Manual end to end testing
  • Automated end to end testing
  • Access Inbox. Examine your read and unread emails.

Manual end to end Testing:

Manual testing is a common software testing performed directly by a human tester. This helps testers identify test cases and uncover hidden user interaction paths in the system, which provide the required information to start automating these tests in the future. Tests that were built manually can also become automated tests.

Manual End to End testing can be conducted in two ways:

  • Horizontal End to End Testing:
  • Horizontal end to end testing looks at an application from a broad perspective. It requires software development teams to have well-defined workflows and established test environments. In this type of testing, a single test workflow can span multiple subsystems. A plan for simultaneously testing UI, a database, and email integration is an example of a horizontal end to end test.

     
  • Vertical End to End Testing:
  • Vertical end to end testing is a way of testing an application by breaking it down into layers, which can then be tested individually. It is often used before horizontal testing because of its granularity. For example, if you are testing user interface subsystems, you can easily identify and fix bugs.

Automated End to End Testing:

As your project continues to grow, performing all end to end testing manually will become impractical. Automated user-interaction testing is essential for projects with large user interfaces because of the complexity involved in a single action; many actions can be taken depending on the user's inputs. Manual tests are time-consuming and challenging to manage as a project grows in size and complexity.

Once you’ve decided on the test cases, write them as code and integrate them with an automated testing tool. For example, you can use a CI/CD pipeline to automate the end to end testing of software. As new features are added to software at increasingly faster rates, you can catch bugs quicker as automation has the entire code base automatically checked against the test cases each time you add new code.

Check out our detailed guide to learn how you can perform Cypress End to End testing.

Tools Used for End to End Testing:

Here are the top tools that are used for end to end testing:

LambdaTest:

LambdaTest is an end to end testing platform for Selenium, Cypress, Playwright, Puppeteer, and many more test suites. With LambdaTest, you can perform end to end testing across 3000+ browsers and OS combinations. It offers many features that developers need to scale end to end tests, including dashboards to monitor flaky tests and parallel tests. Now they are taking performance one step further with their new HyperTest offering.

Selenium WebDriver:

Selenium WebDriver is an open-source test automation framework that allows you to write and run tests for your web application in various environments. It allows you to interact with the elements of a web page, including textboxes, checkboxes and buttons. Selenim WebDriver also provides ease of infrastructure management by providing the test environment for your team.

Selenium Webdriver js is a tool that allows you to click and access elements within a web page using Javascript, making it easier to test dynamic components of the DOM. You can use multiple programming languages such as C#, Python, Ruby and Java with Selenium Webdriver js.

If you have an API-only business, you have frontend and admin components of your application. Therefore, end-to-end tests ultimately test frontend applications.

Selenium is the standard tool for performing end to end testing. This tool provides an API to talk to the web browser and interact with the DOM, allowing you to fill in inputs, click around on buttons, or type into text fields. With Selenium, you can automate anything a real user would do with your application.

Although the Selenium WebDriver API seems intimidating at first glance, creating a few convenience functions to alleviate some of its complexities will get you productive in no time.

The best way to write efficient and reliable e2e tests is to understand a few basic concepts about Selenium WebDriver. Once you understand these concepts, writing e2e tests will be extremely easy and fun, and help you increase the test coverage of your applications.

Want to know more about Selenium WebDriver? Check out our tutorial.

Cypress:

Cypress is a JavaScript-based front-end test automation tool that you can use to debug your UI. Cypress provides a built-in debugging feature and allows you to set up waits and retries to ensure that all your tests are passing. It also allows you to schedule your test executions within a CI/CD pipeline to automate this process.

Cypress is a new testing platform that aims to overcome the challenges of automated frontend testing for applications built with React and AngularJS. It's quicker, easier, and more reliable than Selenium for running tests on real browser instances. Since Cypress executes tests on a browser instance, you wouldn't need to download browser drivers.

Cypress is a faster, better solution for debugging end-to-end tests and running them parallel to any pull request as part of CI. It’s easy to learn for developers who are already familiar with JavaScript.

End to end testing with Cypress is the go-to choice for testing the integration between two or more systems. Doing so can ensure that various dependencies of an application are working accurately and that accurate information is being communicated between multiple system components.

Want to know more about Cypress? Check out our tutorial.

Playwright:

Playwright is a powerful and new tool that helps you build modern web applications and offers you end-to-end testing and cross browser testing capabilities.

Although Playwright is new to the market, it already has several features that make it a strong competitor. People who want to migrate from Selenium to Playwright can do so quickly since Playwright supports C#, Java, and Python. Programmers aren't limited by the language they use; Playwright's first release was in January 2020 and its popularity has grown steadily since then.

The process of writing, automating, and maintaining E2E tests is tedious and time-consuming. Testers have found that having to write E2E tests is not fun at all. The flakiness of the tests made them difficult to maintain. Playwright takes care of auto-waiting for elements to be ready for execution, like clicks and page navigation.

Playwright provides options to capture screenshots while an E2E test is running. Options include taking a screenshot of the entire page or a specific element on the page. In addition to saving the screenshot, you can get a buffer with the image and post-process it. If an E2E test fails, the page screenshot will be handy for determining what went wrong and fixing it.

Playwright is an open-source library to help you write end-to-end tests for your application. Using the codegen feature and taking advantage of its built-in assertions and mocks, you can get started with Playwright's library in just a few minutes.

Want to know more about Playwright? Check out our tutorial.

Puppeteer:

Puppeteer is a new framework that allows testers to perform headless browser testing of Google Chrome. Puppeteer testing will allow for easier and faster end to end test automation of web pages and applications.

Puppeteer is a browser automation tool built on top of Chromium's DevTools Protocol, a protocol for communicating with browsers from user scripts. It lets you run headless Chrome in Node.js to perform a majority of tasks performed by a developer when debugging, such as handling requests and responses, locating elements, network traffic and so on.

Puppeteer can help you automate your end-to-end testing. With Puppeteer, it’s as easy as writing a few lines of code. No special configuration is needed to get started. When you download Puppeteer, it installs its version of Chrome. But if you prefer to use a browser you already have installed, you can install the puppeteer-core package.

Want to know more about Puppeteer? Check out our tutorial.

There are more frameworks that you can leverage for E2E as well like:

End to End Testing Best Practices

End to end testing is the type of testing that mimics the experience of a real user using the application. Here are a few best practices to get the best out of end to end testing:

Test Repeated User Scenarios:

You may be unable to cover every possible use case and path through the application. Avoid testing the edge cases and focus on the most common scenarios. Integration or low-level unit testing may better fit the exception cases.

Prioritize the Right Aspects:

When testing an app, start by testing the features that will impact your business the most, whether it’s customer experience or ensuring a failure does not affect your revenue stream. It’s better to address those aspects that have a significant impact on your business first.

Make Testing Realistic:

The way most people use a website is not by clicking a few buttons and moving on. They read, look at images, or pause between actions. End to end testing should mirror real-life interaction as much as possible.

Error Monitoring:

End to end testing environments can be complex because they encompass the whole application. However, by resolving as many errors as possible before doing end to end testing, you can reduce the number of problems to investigate.

API Testing:

When coupled with API tests, end to end tests can help developers determine whether a front-end failure is caused by a functional error or an API call error.

Optimize Testing Environments:

You can facilitate the testing process by creating an optimum test environment. This allows for minimal setup when it’s time to test and a fast way to clear data so your test environment is ready for the next test.

E2E Testing Checklist

E2E is not just about testing the user interface because a user interface is made of numerous distinct components.

The content for a blog site may be fetched from a database via an API. Therefore, the frontend design, the database, and the API must be tested independently and in conjunction in this situation.

Here is a list to use as a guide for E2E tests:

  • Database: It would be necessary to test the database that is used by your system. You might perform tests to ensure that data is correctly organized, stored, read, and updated.
  • Performance: A website may navigate properly, but user experience depends on speed. Therefore, testing a page's or feature's usability is crucial.
  • Security: The degree of an application's user and organizational security is determined by its web application security. In this situation, vulnerability testing techniques are very crucial. The primary driver for testing in the first place is functionality. Every feature must work as intended. Unit tests may also be helpful in this situation.
  • Usability: Given their intended purpose, components must be helpful. Tests must cover events (such as clicks on components), proper navigation, and other issues because users are just as vital as the technology.

Running End to End tests at LambdaTest:

If you lack the required testing tools, testing can always be arduous. LambdaTest offers a cross browser testing platform called that can help developers and testers get beyond the current testing difficulties involving various devices and supported platforms.

Once you have registered and logged in, you must follow these steps to run Real Time Ionic website and web application testing on the LambdaTest platform.

  • Navigate to the Real Time Testing section in the menu on the left.
  • Type the website URL in the Real Time Testing for testing. Choose the BRAND, DEVICE/OS, and BROWSER for mobile devices, as shown in the below screenshot.
  • Post selecting it, click START. You can launch your website using the required configuration.
  • You may access various functions when the website has launched, including the ability to capture screenshots, video recording of a test session, log bugs with a single click, and more.

Conclusion

End to end testing is essential for assessing how a user will interact with your programme. Evaluating the user experience from beginning to end provides more assurance regarding the quality of your application than simply testing if a button function or a model appears.

End to end testing implementation methods such as horizontal testing, vertical testing, and the distinction between manual and automatic testing were all covered.

Through this extensive end to end testing tutorial, we hope to answer every question you have regarding end to end testing.

You can also use LambdaTest's cloud platform to run your first end to end test.

Happy Testing!

Frequently Asked Questions (FAQs)

What does agile mean by end to end testing?

End to end testing is a type of software testing where the whole life cycle of the software product is examined to see if it is functioning as required. E2E testing is used within the agile process to deliver quick responses and speedier solutions.

How to simply define E2E?

End to end testing is a method that verifies that the application flow functions as expected by evaluating the full software product from start to finish. It specifies the system dependencies for the product and guarantees that all integrated parts function as intended.

Are end to end tests challenging?

Because they require creating, deploying, opening a browser, and doing tasks within the application, these tests take the longest to complete. Because the failure range for E2E tests has been enlarged to include the entire application, it is frequently challenging to identify the problem.

Which testing tool is used from beginning to end?

You can create automated end to end tests with Endtest, an automated testing solution that offers a complete testing suite. Access control, parameterized testing, and cross-browser compatibility are just a few of the tool's adaptable features.