What is E2E (end to end) Testing?
Plainly speaking, end-to-end (e2e) testing is one of the methodologies used in the software development lifecycle. Its purpose it to test the performance and functionality of the entire application (from beginning to end) in order to make sure it behaves as expected. E2e testing defines the product’s system dependencies and checks if all components and integrations work by running tests and validating steps on every layer of the application or software.
Another important goal of the end-to-end testing is to test the software from the end user’s perspective. By simulating real user scenarios and replicating live settings, you validate the system under test but – more importantly - avoid a major risk of any subsystems crashing or even your system breaking down completely. A failure of one software layer (e.g. API) or any external database might make the whole product unstable. That means that end to end testing is an inherent requirement for software. The testing strategy should maximize the test coverage, increase confidence with each release, and, at the same time, reduce project time and costs.
END TO END TESTING VS FUNCTIONAL TESTS
It might be useful to shed some light at the very beginning on the differences between functional and e2e tests so the two are not confused. End to tend tests cover multiple applications and user groups (and the way they work across apps) whereas functional tests are limited to a single piece of an app or a code (and test a single user’s behavior). The purpose of testing also differs – for e2e testing it is to ensure that the process run uninterrupted after introducing some changes to the system. Functional tests are clearly to test if the software meets the acceptance criteria.
Further on, we will discuss how to implement e2e testing, review the end-to-end testing methods, explore the automated end to end testing and list both the challenges as well as the benefits of such testing. We will round up with best practices for end-to-end testers.
How to implement end to end testing?
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Review the testing requirements for validation of end-to-end testing results
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Set up testing environments
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Define the necessary processes for your system and its subsystems, integration, etc.
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Describe the roles and responsibilities of the systems mentioned in point 3.
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Outline the testing tool and testing framework(s).
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List the requirements for test case design.
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List the input and output for each system (point 3).
Once all done, you are ready to kick off your end-to-end testing.
End to end Testing Methods
To make the end to end testing as effective as possible, you can lean on different testing approaches. The two most popular e2e testing methods are discussed below:
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Vertical e2e testing:
this method means testing in layers. Tests happen in hierarchical (sequential) order. Each component of the system or software is tested from start to finish. The vertical method of end to end testing is usually used for testing the critical parts of complex systems which does not involve users or interfaces.
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Horizontal e2e testing:
another commonly used method of testing occurs across the context of multiple applications (thus, horizontally), however within a single ERP application.
Automated end to end testing
End to end testing can be done both manually and automatically. The best approach is to combine both. If you want to make the testing less complex and save resources, automate the user-interaction testing. For automated testing, with a modern and comprehensive automated tool, you can use test plans and test cases that have been prepped manually.
You might want to switch into automated end to end testing as your testing project grows. With more and more complicated use interface, increasing number of user actions, the growing number of testing cases (growing with new number of new software functionalities) and the need for higher test coverage, automates end to end testing seems much more manageable. What the automation will help you with is also catch the bugs early on (the code will be automatically checked against the test cases when adding new code), thus shortening the time of the testing project and saving money.
Challenges in end to end testing
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End to end testing is time-consuming:
you need to understand the product very well in order to create test cases. And although you might learn all the paths of the software product, testing each of them takes tons of time. Instead, companies prefer to use unit tests or integration tests and e2e testing covers only the high priority user workflows.
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Difficult test design:
as end to end testing simulate real-user behavior, test case design is multilayer and quite complex. For instance, you need to take into account different browser specifications. In order not to go over the budget, in test-driven environments end to end testing might not be a feasible solution.
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Understanding user goals:
end to end testing should not focus on the app itself but rather on the user’s issues and how they want to get rid of specific issues. Not having a good understanding of user intentions might be problematic for the e2e testing approach. User research takes time (and money) so teams often tend to rely on “beta testers” for an application, rather than gain real users’ perspective on the software.
Benefits of end to end testing
When talking about who can benefit from end-to-end testing, we need to differentiate two groups:
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IT managers:
e2e simulation tests let the know exactly how a failing test would impact the user
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Testers:
writing tests to mimic real-user behavior helps with prevent problems with testing ahead.
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Verify your application health:
you make sure that the software is functional at every level and check its performance across different environments
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Reduce testing cost and effort:
a comprehensive approach to testing the app each step of the way reduces the need to repeat tests, results in fewer bugs and breakdowns, thus reducing the costs and time spent on testing, too.
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Increase application productivity:
end to end testing is executed after every iterations which means faster detection of bugs. Fixing the issues early on, before proceeding with production environment, ensure that the application operates seamlessly.
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Maximize test coverage:
with testing many different subsystems, you expand your testing coverage and introduce new test cases into the testing scenarios.
Best Practices for end to end testing
To increase testing efficiency coverage and use the full potential of the testing tool in hand, you might need to follow one of the best practices for end to end testing. What are they?
- Timing of testing: Prior to testing, developers and designers create a list of functionalities, features and UI that need to be performed. Teams also prepare conditions for factors that may impact the interface options. During testing, data flow is tracked between the systems to identify flaws and dependencies. E2E testing is done on the finished product and systems. The second run of tests take place if the system does not output what is expected or if a problem occurs. If it does, the team will have to record and analyze the data, find the origin of the issue, fix it and run retests.
- Metrics: for end to end testing, you might also want to rely on test metrics such as:
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Test progress tracking:
test progress is tracked on a weekly basis. You should get the details of test completion percentage, such as the number of failed, executed, valid test cases.
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Test case preparation status:
this determine the specific position of the test cases being prepped (as opposed to planned test cases)
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Defects status and details:
with this metric, you focus on a weekly percentage of open vs closed defects. Defect distributions are based on priority and criticality.
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Environment availability:
this gives you the actual number of hours scheduled for and spent on testing.