What is End-to-End (E2E) Testing? | A Detailed Guide
As a software tester, you know that End to End testing is essential for quality assurance. But what is it? And more importantly, why is it important?
In this blog post, we’ll discuss the basics of E2E testing and explain why it’s so critical for ensuring quality software. So read on and learn everything you need to know about this essential testing process!
What is End-to-End Testing?
End to End Testing is a software testing technique that makes us test the entire application from start to finish, in an environment that is similar to production . It checks the integration of the software’s dependencies ensuring that all the interfaces, databases work together as expected.
End to End Testing tests how the application communicates with hardware, network connectivity, external dependencies, databases, UI, API layers, and other applications.
End to End testing complements other forms of testing like unit testing, system testing, functional testing by providing additional coverage and verifying the system as a whole.
Why is End to End Testing necessary?
When programmers develop new software, they create a small unit and test it. This creates an easy to follow feedback loop. Then they integrate these units into modules and test them. In an ideal scenario, this process would incrementally cover all parts of the system but it’s rarely the case.
Software applications these days are highly complex and interconnected with multiple subsystems. Even if a single system fails, it would fail the entire software.End to End Testing can increase the coverage of our testing as it checks the entire flow including all the subsystems similar to the user environment. It detects issues and decreases system failures.
It avoids the risk by
- By verifying the backend of the system.
- Interacting with different layers of the architecture as it checks the overall functionality.
- Increasing the test coverage and scope of the application.
- Performing repeatable tests at different points and processes in the application.
- Involving the front end in the testing ensures a better user experience.
How to perform E2E testing?
Based on the requirement of the project, end to end testing might vary. Here is a list of the most common steps used to perform E2E testing:
Step #1: Here we have to analyse the requirements and have a clear understanding of the expectations.
Step #2: Thoroughly analyse the software and hardware requirements.
Step #3: Set up the test environment based on the given requirements.
Step #4: Study the main system along with the subsystems
Step #5: Describe the responsibilities of the system, i.e to know the expectation of how the system should respond.
Step #6: List down the testing methods required for the testing along with the tools, languages etc.
Step #7: Develop test cases and make sure that we trace it by the requirement matrix.
Step #8: Before running the test in each system, save both input data and output results.
Implementing End to End testing for a large organisation can be a laborious process especially for an interconnected application with multiple systems. Thus the first step of implementation would be to pick out the most critical business component and start with that.
End to End Testing Example
Let’s consider an example of a customer using an E-Commerce Application and see how we can apply End to End Testing to this scenario
Step #1: Log in to the application
Step #2: View different products
Step #3: Select an item and add it to the cart
Step #4: Confirm and place the order
Step #5: Perform the payment
Step #6: Check the order details.
Step #7: Log out of the application
The above scenario might seem simple from a user’s point of view but in the background, so many other systems work together.
Login involves the UI and database to process the access request. Other processes involve payment gateway with third parties ,updating the vendor about the order, updating inventory, pulling out price details, applying discounts and more, to perform these multiple systems have to work together.
Here is a tester, we have to verify the user functionality, conditions and test cases. Ex: check the functionality of the third-party integration for payment
How to create End-to-End Test Cases?
Designing a test case for unit testing is completely different from API testing. In E2E testing we’ll go through many blocks of code and multiple APIs simultaneously. For creating End to End Test Cases, we have to break down the user’s flow into small steps. Here we check each functionality along with its integration between different systems and data integrity between them.
Here are some processes that will help us to build efficient, accurate test cases for our end to end testing.
- Define the Scope of E2E
- Bugs to Target
- Define User flows
Define the Scope of E2E
- It is impractical to test every functionality in the application for an end to end testing.
- The best way to optimise the scope of testing is to perform user flow. We can ensure coverage by testing the path which customers usually use.
- Here we have to collect data and analyse those workflows.
Bugs to Target
- E2E makes sure that communication between different systems and subsystems works as intended.
- The validation should make sure that integrations and interactions in the application perform as expected.
- Here we will find defects at these interaction points where the system interacts internally with subsystems and externally with users.
Define user flow
- A bigger test suite might result in high maintenance costs, it will be complex to add more modules further.
- To avoid such issues, we can split our test cases into two groups: core and edge.
- Core cases cover the critical functionality, frequently used workflows by the user.
- Edge cases cover rare scenarios which are unlikely to occur, but if these happen can fail the application.
- Running core and edge cases for every build can provide us proper feedback.
End-to-End Testing Lifecycle
End to End Testing Life Cycle consists four phases:
- Test Planning
- Test Design
- Test Execution
- Result Analysis
Test Planning: End to End Life Cycle is similar to STLC, here we plan the important phases, it helps us specify the critical task, schedule the timeline and resources for the testing.
Test Design: In this phase, we generate test cases, test specifications and perform usage analysis, risk analysis and then schedule tests.
Test Execution: Here we execute the test, verify the application from end to end. We’ll document the issues, observations and remarks.
Result Analysis: In this stage, we analyse and compare the test results.
End-to-end Testing Methods
We can perform End to End Testing using two methods, depending on our testing goals we can choose it.
Horizontal E2E testing
It is most preferred for End to End Testing Method by testers. In horizontal testing we test every workflow by testing every application from start to finish, to check if the workflow functions properly.
- We perform Horizontal E2E testing from a user’s point of view.
- It checks whether the user can navigate to a different part in the application and perform actions as expected
- It helps us detect bugs that we might have missed during unit testing.
- We can perform it in every phase of the business workflow, it can help us map the requirements to the application developed.
- It ensures the interrelated process works correctly by testing beginning to end.
- With this approach, we can get more coverage on the functionality of the application.
- Usually, we perform this testing when the environment is stable, at the end of the release cycle.
Prerequisites for Horizontal Testing
As it verifies the workflow across multiple applications and subsystems, the test environment needs to be set up in advance.
Advantages for Horizontal Tests
- It leads to testing the system from a user’s perspective.
- It prevents the bugs from reaching the live environment.
- It makes sure that we cover the business logic requirements.
Let’s take an e-commerce application for this example. In Horizontal testing, we would test the sign up/login, product search, add to cart, payment flow, confirm the order and sign out.
Vertical E2E testing
It is usually used for critical modules that consist of complex systems. It validates the system in layers, here we conduct tests in sequential, hierarchical order. It helps us test the software from start to finish for all-inclusive testing.
- Vertical testing focuses on layers, it tests each layer of the application’s architecture.
- We’ll work through subsystems that are independent from one another at a granular level.
- Here we start with unit testing then continue testing both UI and API levels.
- We perform it in either hierarchical or sequential order.
- It is usually done when there’s no UI in the system or the UI is at a high level of complexity.
Prerequisites for Vertical Testing
As we are focusing on the architectural layer of the application, we would need support from testing or development strategies such as behaviour-driven development(BDD), test-driven development(TDD), or continuous testing(CI/CD).
Advantages for Vertical Tests
- It ensures high code coverage.
- It builds more focused tests.
- It results in faster test execution.
- It is useful to test critical software safely.
In Vertical E2E testing, we test the application program interface(API).
E2E Testing Checklist
Here’s a list of checklists for End to End testing:
- Check the database of the application, make sure that the data stores, organises, updates and reads properly.
- Check the performance of the application, make sure that your software product has speed as it is one of the important components of user experience.
- Check the security of the application, make sure the application is secure for both user and the company, try vulnerability tests and other security testing techniques.
- Check the functionality of the application, make sure each feature functions as expected, we can use unit testing here.
- Check the usability of the application, make sure that the user finds it simple to navigate and easy to use.
When to perform End-to-End Testing
- We can execute End to End Testing when the system is stable.
- We can perform it at any point of time in the project to verify the integration.
- We conduct it after system testing when all the components are integrated.
- Usually , testers prefer it during regression when there’s an incremental feature in the already existing system.
Benefits of End-to-End Testing
- End to End testing is usually automated, thus reducing repetitive efforts
- It tests the application from a user’s perspective.
- It expands the test coverage as it tests the application from beginning to end.
- It ensures the correctness of the application as it checks both the functionality and architecture of the application.
- It helps in detecting bugs and reducing the number of issues found in the live environment.
- It checks the business logic of the application.
- It can reduce time and cost
- It ensures that each functionality not only works individually but together as well.
Challenges in End to End Testing & How to Overcome Them
End to End testing is a useful form of testing but it comes with its challenges.
Challenge #1: Building Workflows
An application will have n number of functionality and considering that an application is a combination of third party systems,subsystems and APIs, it may result in thousands of test cases.
Solution: Here the team must brainstorm and come up with critical scenarios and prioritise them. We can get feedback from customers as well.
Challenge #2: Test Environment
Getting a test environment similar to production is not easy. Several elements need to be set up to consider it as a replica of a live environment.For example , the environment should connect a third party application for banking transactions etc.
Solution: Here the team can opt-in for a good testing platform which gives us a lot of privileges to plugin other systems. Communicate with the third party about our testing needs.
Challenge #3: Long term Maintenance
End to End testing is an incremental process, whenever we add a new feature to it , we have to develop a new set of cases. Over time it would be difficult to add new sets without disrupting the existing ones.
Solution: Here we can define a proper structure for the test suit from the start and re-organize it whenever possible to maintain the scripts.
Challenge #4: Test flakiness
End to End test suites have a reputation of being unstable. One day the test might run properly, the other day the test would fail. Because E2E validates different parts of the application, it is difficult to isolate the problem. Sometimes the testing team isolates the issues on the whole which might lead to a decrease in the value of the automation suite.
Solution: Here we can keep track of the test failures, use our testing tools to their efficiency. Most importantly not ignore test flakiness, by tracking the test failure, by that we will get an idea where the issue arises and work on fixing them.
Challenge #5: Slow Test
As end to end covers the entire stack and tests every functionality, the run time for the test can be long. In the world of continuous constant feedback, having such a long run time can negatively affect the efficiency of the development and testing team. Accelerating our E2E testing depends on various factors like the architecture of your application, any dependencies or reliance on external services, network connectivity and other factors.
Solution: Here we can avoid the time consumption functionality by using mocks to simulate the behaviour. We can also set up the right data beforehand and build our test suite such that it runs concurrently.
Best Practices for End to End Testing
- Prioritise End-user workflows.
- Run the entire test suite concurrently.
- Automate the End to End testing process.
- Test only the critical and frequently used functionality.
- Deploy the software application in a production-like environment.
- Maintain proper structure while performing testing, as it contains several components it can get complex.
- It should be easy to set up the test environment and after testing it should be easy to erase the data and dismantle it.
Metrics for End-to-end Testing
We can perform End to End Testing efficiently, effectively, save time and effort by tracking our progress through proper metrics. These metrics are very useful as they help us to understand the status of our project.
Some of the best ways to measure the success of the E2E testing :
Test case Preparation status: We can track the status of preparation visually by comparing the current set with the number of test cases initially planned.
Test Progress Tracking: We can track the test progress every week. With this we can determine how many tests have passed, failed, blocked along with the defects.
Defects Status and Details: We can look at the weekly percentage of opened and closed defects. Along with the defect distribution driven from on severity and priority of those issues.
Environment Availability: Here we’ll be measuring two components, time scheduled in the test environment and the time spent performing tests in the test environment per day.
E2E Testing Design Framework
In general, the test case for End to End testing verifies the workflow of the application from the beginning to the end of the flow.
Here are some activities we have to consider while performing End to End Testing:
- User Functions
- Test cases
In this process, we should do the following:
- We have to list down all the functionality of the application along with the interconnected subsystems.
- For every individual functionality, we should track and record all the actions i.e verify the input and output data for those features.
- Analyse the connection between the user functions.
- Identify the functionality that is independent, dependent, reusable, etc.
To identify the conditions for the functionality, we should do the following procedures.
- Find out the conditions for every user functionality.
- These conditions would include date conditions, timing, other factors which would affect the functionality
To create the test cases for End to End Testing, consider the following steps:
- For every individual functionality that we are about to test, build multiple test cases.
- For every condition, create at least a single, separate test case.
End-to-End Tests Vs Functional Tests
|End to End Testing||Functional Testing|
|In End to End Testing, we test multiple applications, subsystems and user groups.||In functional testing, the testing scope is limited to a single functionality.|
|It ensures the entire system continues to work properly after making changes.||It ensures that the software functionality meets the acceptance criteria.|
|Here we test in a way multiple user access several part of the system.||Here we test in a way that a single user accesses the application.|
|Here we validate each step of the process.||Here we validate the input and output of the system.|
End to End Testing Vs System Testing
|End to End Testing||System Testing|
|End to End testing validates the software application along with the interconnected subsystems.||System Testing validates the software application against the functional requirement.|
|It checks the complete end to end flow of the system.||It checks the systems functionality and features.|
|Here we consider all the interfaces, subsystems, databases and backend process for testing.||Here we consider only functional testing and non-functional testing.|
|We conduct it after system testing.||We conduct it after integration testing.|
End to End Testing Tools
Perfecto is a leading testing platform built in the cloud, which is used for testing both web and mobile applications. Here it helps us access the cloud for end to end testing. We can test on real mobile devices, macs, VMs and other simulators.
- Perfecto can automate the software with code or scriptless or both.
- It executes the test in real, virtual devices simultaneously.
- It easily integrates with other frameworks which increases the efficiency of the test.
- It is commercial software, so we’ll get support from their team if you are facing any issues.
- It has key features like scriptless automation, real user simulations, remote device access and AI-driven analytics.
Katalon Studio is an automation tool that can make out end to end testing less complicated. It has three core features that can be applied in E2E testing, Recorder, built-in keyword and custom keywords.
- Kantalon reduces the hassle of creating user journeys, it has this recorder feature that records our movement in the application to create good user journeys.
- It seamlessly integrates into our system and automates the process, especially continuous testing.
- It is a simple yet scalable solution for our automation requirements.
- It has codeless experience for testers and infinite extensions for experts.
- It provides automation solutions for every industry.
Selenium is a free open source, automation testing framework which is used to validate web applications. It is the most widely used automation framework. It lets you script in programming languages like Java, Python, C#, Ruby, Node JS, Pearl etc.
- Selenium can test the application in various web browsers like Chrome, Firefox, Safari, etc.
- It is a platform-independent framework, we can deploy it in Windows, Mac and Linux systems
- It can be integrated with other tools like TestNG, JUnit for test management.
- Most browsers have built-in support for automation using Selenium.
- Cypress can be used for cross-browser testing and it’s universal.
- Cypress automation is easy to set up.
- Cypress has debugging capabilities.
- Cypress can provide fast, reliable and consistent results.
- Cypress takes screenshots and videos automatically if there’s an issue.
- We can use spies, stubs, clocks to verify and control the behaviour of server responses, functions, or timers.
Cucumber is the world’s leading software testing tool that supports behaviour driven development. It is an open-source software tool written in Ruby.
- Cucumber bridges the communication gap between the business and technical associates by collaborating on executable specifications.
- Testers without in-depth coding knowledge can script using cucumber.
- Compared to Selenium, Cucumber has faster plugins
- It supports various programming languages.
- It is flexible with different platforms like selenium, Ruby on Rails, Spring framework etc.
Leapwork is a no-code automation tool that makes it easy for businesses to automate the repetitive process. It is commercial software.
- It supports automation for both web applications and desktop applications.
- It easily integrates with CI/CD pipeline, it slots you into existing pipelines with tools like Jenkins, Jira, TFS, and Bamboo.
- It has a built-in test reporting system that collects the data and presents it in a visual form.
- It simplifies the test development process by building version control systems, it is easy yet traceable.
- It is robust, secure and low maintenance for automation requirements.
- It is easy to learn.
End to End testing plays a crucial role in ensuring that the user gets a good user experience. It is an affordable way to ensure that our software works the way we and the end user expects it to. Here the end goal is to eradicate regression bugs and save as much time in manual regression. E2E is a long term plan, it might not show an instant benefit but we build up a good test suite and do some trial and error with it. It would bring out the great results.