A guide to end to end testing (definition, steps and FAQs)
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Within software development, QAs and developers typically test their applications prior to release. End to end testing is a form of software test which determines the overall functionality of the application. If you're interested in software development or QA work, understanding what this kind of testing means can be very useful. In this article, we explain what end to end testing is, the elements within it, how to conduct it, present an example and answer some frequently asked questions.
What is end to end testing?
End to end testing (E2E) is a method for testing software applications which ensures that they're functional for the end-user. It helps to ensure that all of the integrated pieces of the application are fully functional in a wide array of use cases and scenarios. The main premise of this type of testing is adopting the perspective of the end-user and determining how they might use the application, going through these scenarios and checking for any issues with the software.
E2E testing is therefore typically one of the last stages in software testing, as it's often the most thorough and comprehensive form of test. It involves determining the functionality of the application and all of the various coding elements. E2E testing is particularly useful for applications which have many layers and integrations, as an issue with any one of these could adversely affect the entire user experience.
Elements of E2E testing
There are multiple factors involved in the E2E testing process. Considering these during an E2E test ensures that the likelihood of identifying an issue is as high as possible. Here are some of the main elements of an E2E test:
A test case is a scenario where the end-user is attempting to use a certain function of the application. Envisioning various test cases can help with a more thorough E2E testing process. Software testers and QAs often try to assign at least one separate test case for every condition they can envision. They also typically list the various user functions of the application and develop multiple test cases for each to ensure that the E2E is as thorough as possible. A test case includes multiple steps in an application's workflow.
A user function or action is a scenario where the user attempts to access one or multiple functions of the application. Testers consider these various user actions and test the software to evaluate its effectiveness in completing each of these. A key aspect of this is when users attempt to use multiple functions in combination, which testers try to anticipate. Testers then establish the independence or reusability of these functions, identify how they relate to each other and list interconnected sub-systems.
An environmental variable or condition is a factor which might affect a user function. These are often external to the software application itself and considering them helps testers evaluate the application's performance in various circumstances. An example of an environmental variable is the operating system in which the application is running, the timing of the action, the hardware in use, which browser the user is running and integrations with other software. Testers try to consider all possible environmental variables when running an E2E test, allowing the application to be as accessible as possible to the greatest number of end-users.
How to conduct an E2E test
Here is a list of steps to follow if you want to conduct an E2E test:
1. Define ideal functionality
Prior to testing the software application, it's necessary to first have some criteria with which you can assess it. By defining the application's ideal functionality, you can then compare actual functionality to this to see how effective it is. This includes a description of how various interactions are intended to behave, how the software responds to user inputs and the functionality of its various features.
2. Set up the test environment
It's crucial that you have a stable testing environment which can return replicable, consistent results. This ensures that you can accurately identify the source of any issues in the software when they occur. The testing environment includes the operating system, browser and hardware on which you run the application. If you're going to test it on different browsers or operating systems, then each of these requires a separate setup to ensure reliable results.
3. Identify test cases
Based on the ideal functionality of the application and your understanding of possible end-user behaviour, you can start to make a list of possible test cases. These are the scenarios which users may encounter while using the application and involve the various functions necessary for it to operate. It can also be a good idea to change the sequence of various actions to see how the software might respond in these circumstances, as different users might use the application differently.
4. Establish metrics
Once you know what you want to test and what the ideal functionality is, it's a good idea to consider the metrics you're going to use for recording the results. These can include the loading times of pages within the application, the occurrence of crashes or freezes and the presence of any input lag. You can also determine what an acceptable level is for each of these metrics, while also taking into account hardware and other factors.
5. Run multiple tests
After you've run a test for a certain set of conditions, it's a good idea to change the order of interactions, the environment or other conditions. Running multiple tests like this in various environments ensures that your E2E test is as comprehensive as possible. Make notes of any metrics you observe during this and compare the functionality of the application to your ideal functionality. Remember to consider all of the E2E test elements when going through your tests.
E2E testing example
The ideal functionality of the software application typically determines the complexity of the testing process. Here is an example of an E2E test framework for a text-based chat application which runs through browsers:
able to instantly send text to multiple users of the same application
runs in the top three most popular web browsers
runs on the two most popular operating systems
runs on smartphone browsers for the two main operating systems
can send audio, image, video and text files up to 10MB in size
Windows OS with Firefox
Windows OS with Chrome
MacOS with Safari
MacOS with Firefox
MacOS with Chrome
Android with Firefox
Android with Chrome
iOS with Safari
iOS with Firefox
iOS with Chrome
Test case steps
Cpen the application in a browser.
Send a message to another user.
Send an audio file to another user.
Attempt to download a received audio file.
Open in multiple browser tabs.
Check for updates to background tabs.
Check share functionality on Android and iOS.
Close the application.
Re-run steps one to eight for all user conditions.
Frequently asked questions about E2E testing
Here are some frequently asked questions about E2E testing, together with their respective answers:
What's the difference between E2E testing and system testing?
Both of these types of testing evaluate system and software behaviour, and in many cases overlap to some extent. The primary difference is what they test and the order in which you'd perform each of them. System testing specifically tests a software application within the relevant integrated system requirements, checking whether the application is within compliance and is both reusable and reliable. E2E testing is typically a subsequent testing phase and is more comprehensive, including factors like back-end processes.
Is it possible to automate E2E testing?
Yes. Manually performing comprehensive E2E testing can be very time-consuming and even tedious, especially with complex applications which have a lot of integrations. A possible solution is to automate the E2E testing process, which can deliver consistent, reliable results in a fraction of the time necessary to test manually. Some third-party solutions exist which can provide this automated testing.
Please note that none of the companies, institutions or organisations mentioned in this article are affiliated with Indeed.
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