An Introductory Guide to End-to-End Testing

End-to-end Testing

Today's web and mobile applications and software, in general, are more complex than ever. They rely on a network of subsystems, including but not limited to external databases, UI and API layers, and third-party integrations. While this helps with optimal functionality and performance, a failure in any subsystem could spell doom for the entire application. Thus, there's a need to thoroughly test all the application's layers and connected subsystems before release.

Admittedly, the testing team will have to execute various tests during the app's testing life cycle. However, it's safe to say that none promises the coverage or thoroughness of end-to-end testing.

What Is End-to-End Testing?

End-to-end testing is a software testing technique that verifies the functionality and performance of an application by replicating real user scenarios. The test goes through the application's workflow from beginning to the end and checks all the operations the app is purported to perform.

How Does End-to-End Testing Work?

The E2E testing process is not too dissimilar from other testing types. It follows a sequential process that starts from knowing the test requirements and concludes at executing the test and recording the result. The following activities typically feature in any comprehensive end-to-end testing process:

Analyze Requirements

This test planning stage usually entails meeting with the software development and business teams to analyze how the application should work. Afterward, you'll map out the scenarios you plan to test before every release. Remember, you'll be testing all possible integrations and workflows. So, it's vital to know what constitutes the proper functioning of the app at every iteration.

Set Up A Test Environment That Matches The Requirements

Once you get the hang of your requirements, the next step is setting up a test environment that can help you validate them. Your test results will only be reliable if your environment matches the production environment as closely as possible. You'll need to deploy test servers, databases, test data, and other necessary parameters at this stage.

Analyze Software and Hardware Requirements

Your application is most probably connected with several databases and systems outside its environment. If you wish to test all the relevant workflows, you'll need various hardware components that mimic the production environment. The software requirement typically refers to the testing tool you wish to use, especially if you'll be automating the test.

Write Down How Every System Needs To Respond

Before designing test cases, you need to know the conditions that each system must meet the benchmark set by you to declare the test as pass or fail. The testing engineer, alongside some members of the software development team, should be responsible for drawing up this list.

List Down Testing Methods Required To Test These Responses

This list will feature a clear description of the testing standards, tools, programming languages, etc., that the testers will follow. It would serve as the ultimate guide for the testing team and ensure everyone is on the same page.

Design Test Cases

Test design for E2E testing typically entails creating multiple cases to cover all the functionalities the user will need while navigating through the software. Also, the testers will need to decide a set of conditions for each user function and assign at least one separate test case to each of the conditions listed.

Run Tests and Save Results

The most crucial part of running automated end-to-end tests is selecting the right tool to use. If your web app doesn't have a UI, the test cases are typically simple, and you can rely on tools like Cucumber library or Postman.

On the other hand, end-to-end tests for applications with UI are typically harder to run. Most of the popular tools available require a decent amount of work to maintain and easily produce fragile tests. A testing tool like PreFlight would be a much better alternative because it can notice UI changes and adapt your test script as necessary.

An Example of End-to-End Testing

End-to-end testing replicates the actions a user would take. The purpose is to evaluate that the results are in line with the expected outcomes. Here's an example of an end-to-end testing process for a BI tool.

  1. A client asks for an insurance quote
  2. The agent issues the policy
  3. The client can see/check the quote that is created by the agent

Benefits of End-to-End Testing

There is no doubt that such amazing features of end-to-end testing provide a lot of benefits. Check out the most crucial ones below.

Better Test Coverage

End-to-end testing incorporates all the subsystems that have been integrated with your application's workflow. A fault or failure in any of these subsystems could lead to a total collapse of your software. The expanded coverage of end-to-end testing helps you mitigate this risk.

Ensures That Apps Are Working Perfectly

During end-to-end testing, your testers rigorously check the performance of each of your app's layers and workflows. Most importantly, they do this from the perspective of the user and replicate live scenarios. This ensures you can be uber-confident that your application is working correctly, and you won't face avoidable problems upon release.

Build Features Quicker

End-to-end testing ensures your application is tested thoroughly, and there's minimal risk of breakdown as you progress on the software development life cycle. Since your developers have the utmost confidence in the functionality and performance of the application, they can add new features without worrying about repeated testing.

Reduce Testing Cost

Testing the application thoroughly from end to end ensures that you no longer have to repeat tests. By doing so, you'll be saving testing costs and time, and your team will be more productive.

Detect Software Bugs

End-to-end testing tests your software product after every iteration. This helps you detect and fix bugs as quickly as possible. Plus, there's a lower chance of bugs making it to the advanced testing or production stage, thereby ensuring your application's workflows operate seamlessly.

End-to-end Testing Methodologies

There are two main techniques for performing end-to-end testing i.e. vertical and horizontal. On the other hand, horizontal testing is

Horizontal E2E Testing

Horizontal testing is the most common E2E testing method. It's done from the end user's perspective and evaluates whether they can navigate the software product and use the functions as expected. The testers test the system across the context of multiple applications while relying on a single Enterprise Resource Planning (ERP) application.

For example, while you're testing an e-commerce system, you will verify that the users can -

  • Login
  • Search for items
  • Navigate through their inventory page
  • Add items to the cart
  • Enter their payment details
  • Checkout

Horizontal E2E testing means running tests one after another in a scenario that is super important for the business. It's always good idea to separate these into smaller tests so that when the test fails, you would know which part is broken. If test fails in Add items to cart that means the app has a functionality that is broken. If you had longer but one test and if it was named "Checkout", you wouldn't know exactly where the test is broken.

In PreFlight, we can use tests in regression (independent) testing or in a E2E (workflow) testing.

Vertical E2E Testing

Vertical testing is typically reserved for testing critical components of software systems that do not involve users or interfaces. It involves testing in layers; the testers will execute the test in a hierarchical or sequential order. Each of the various system components is tested from start to finish before proceeding to the next. An example of vertical end-to-end testing is testing an application program interface (API).

Metrics for End-to-end Testing

Below is a highlight of the metrics or important activities involved in end-to-end testing:

Test Case Preparation Status

Used to determine the specific position of the test cases that are under preparation, compared to planned test cases.

Test Progress Tracking

Test progress should be tracked on a weekly basis. Weekly test progress tracking will provide regular details of test completion percentage, such as passed/failed, executed/unexecuted, valid/invalid test cases, and so on.

Defects Status and Details

It gives a weekly percentage of open and closed defects. Also, weekly defect distributions are based on severity and priority.

Environment Availability

The actual number of operational hours and hours scheduled per day for testing.

How Automation Improves End-to-End Testing

Due to the highly competitive and fast-paced world of modern software development, developers are constantly trying to balance releasing high-quality software and releasing fast. Achieving this balance will continue to be elusive if you do not automate your tests. Below are some of the advantages of automating end-to-end testing.

Automated Tests Save Time & Money

Although the main objection to end-to-end testing is that it's slow and time-consuming, test automation seamlessly solves this problem. With the right no-code automation tool, you can get your end-to-end tests running within minutes. The ideal testing tool will help you create tests simply by using your application and be agile enough to adapt the tests if you change your UI.

Automation Catches Regressions Quicker

Modern software systems are especially prone to regressions because all the internal components are typically interconnected. Even a slight change to a codebase can cause a ripple effect that will affect seemingly unrelated parts of the system. This is why regression testing is an essential part of any software testing process. Unfortunately, manual regression testing takes a lot of time and generally produces unreliable results. The only way to have the utmost confidence in the quality of your software while maintaining the ability to build features quicker is by automating your test.

Automation Gets You Closer To 100% Test Coverage

In theory, full coverage is essential to the success of any end-to-end test. However, it's almost impracticable to achieve 100% coverage when testing software. You can only aim to expand your coverage as widely as possible, and automation helps you achieve that.

FAQs About End-to-End Testing

Here are answers to some of the most common questions about end-to-end testing

What Is The Difference Between System Testing and End-to-End Testing?

System testing is black-box testing that verifies that the total build fulfills the preset business specifications. The test is carried out after integration testing to ensure that the whole software operates as a unit and it comprises both functional and non-functional tests.

On the other hand, end-to-end testing involves testing the application's workflows and dependent systems. It's mainly done to validate the app requirements from the end users' perspective and ensure that it delivers a satisfactory experience for customers. End-to-end testing can only be done after the app passes the system testing stage.

Is End-to-End Testing Part of UAT?

End-to-end testing is typically executed just before or during the user acceptance testing phase. Both tests are conducted to ensure that the application's behavior meets users' requirements, and the user will not have any negative experience while using the app. The notable difference between end-to-end testing and UAT is that testers carry out end-to-end testing in a production environment while recruited end-users carry out UAT.

When Should End-to-End Testing Be Done?

End to end testing is typically executed when the product passes all functional tests, including system testing.

Automate End-to-End Testing With PreFlight

Automating end-to-end tests for applications with a UI remains a challenging task for most testers. It takes a great deal of work to build and maintain your tests on popular tools like Selenium. Plus, a slight change in your UI can lead to fragile tests. With PreFlight, you can create automated end-to-end tests just by using your application. The platform comes with a powerful recorder that enables you to recreate just about everything you can do on your software.

The platform also offers a feature called Workflows. With workflows you can chain tests to be run sequentially. This can cover cases like: A client asks for an insurance quote, and the agent can issue the policy and then the client can see/check the quote that is created by the agent.

Workflows (End-to-end testing) in Preflight

More than just relying on your testers' inputs, PreFlight understands how your product is structured. Thus, if there's any change in your product, PreFlight is agile enough to adapt to the change. This ensures your test only fails when there's a problem with the product and not with the test. Importantly, PreFlight is a no-code tool, and it's easy to use for everyone. The goal is to take the burden off your engineers and testers and ensure they spend less time building and maintaining test cases.


End-to-end testing helps ensure your software delivers a seamless user experience. Although many testing teams may be tempted to skip E2E tests due to the perceived complexity, the potential consequences could be devastating. Instead of taking such a considerable risk and releasing an app with numerous glitches, you should find ways to make end-to-end testing easier. Investing in an automated no-code testing tool like PreFlight can help you take the hard work out of automated testing and ensure your users get the best experience. Do check out our website for more details and if you are a fan of interesting articles, please visit our blog page.