System testing vs End to End Testing: What’s the Difference?

When it comes to creating a high-quality application or software, there are many testing methods leveraged by testers to ensure the application or software meets the best possible quality standards. Each testing method covers different functional and non-functional areas, such as performance, usability, compatibility, and security.

System Testing and End to End Testing are the two popular types of software testing. These terms are sometimes used interchangeably to describe the same thing, but they are, in fact, quite different. Therefore, it is critical to understand what sets these two testing methodologies apart and how these processes ensure the highest quality standards.

What is System Testing?

System testing validates the entire system to ensure that all the components of the ecosystem, including hardware and software, perform as per the expectations. Simply put, it reflects if the application or software performs from a technical and business standpoint, validating the requirement specifications against the system specifications.

This testing is usually performed post-integration testing as the final check before the application is forwarded for acceptance testing. Though it is a black box testing method, system testing may be performed as a blend of white and black box testing based on the project requirements.

System testing imitates the end users and uses the application as they would in real life. Testers check if elements of the system hamper the application’s performance or if the application fails to perform under unfavourable conditions. Errors and bugs, which remain unnoticed in other forms of testing, are identified and reported in system testing. These may be bugs that are associated with performance, security, and so on.

Why is System Testing Important?

• System testing brings down the risk of application failure. Even if the individual components are tested, it is still important to ensure that all the components perform well together.


• It ensures the non-functional and functional requirements are met and customer satisfaction is achieved.


• It validates the entire system to ensure it will work as expected under varied conditions.


• It brings reliability to the application’s quality.


• It is performed to identify the bugs and errors that remain unattended and might sneak into the production stage.


• It allows the testers to feed the same data into existing and new systems so that it is easy to compare the difference in the application behavior when new functionalities are added.


• The results from system testing may be used to wake release decisions. It ensures the application is ready to be forwarded to the user acceptance testing stage.

What are the types of System Testing?

Testers perform different types of system testing at different levels. In practice, it is challenging to implement multiple strategies in a single project. Ideally, the following techniques and activities related to them should be applied. These are:

• Sanity testing
• Documentation testing
• Installation testing
• Functional testing
• Load testing
• Security testing
• Usability testing
• Accessibility testing
• Performance testing
• Migration testing
• Adhoc testing
• Compliance testing
• Reliability testing
• Recovery testing
• Stress testing
• Scalability testing
• Regression testing

What is End-to-End testing?

Digital systems today are more complex than ever and are interconnected with many third-party integrations. Failure of a single component may lead to a hampered user experience or even crash the entire ecosystem. This is where end-to-end testing comes into the picture and prevents the system from crashing or unexpected failure.

End-to-end testing is a software testing process in which the flow of the entire application is validated to ensure the end results meet the desired expectations. This testing primarily aims to verify the user experience by simulating scenarios similar to the real world, validating the application and its components for ease of usage and expected user experience.

Why is End to End Testing Important?

• End-to-end testing validates the back-end layers and the database. The features and functionalities of the application depend on the back end. Hence, it is critical to validate the back-end capabilities to ensure seamless application operations.


• In the case of complex applications where the architecture and workflow are advanced, end-to-end testing ensures that all the functions and third-party integrations are validated to prevent any disruption.


• If the application is cloud-based or service-oriented, End to end testing becomes mandatory. Multiple components and features of the application are tested to ensure the seamless integration of various functions.


• It ensures a uniform UX as it involves validation of the application’s front end. Compatibility across browsers, devices, OS, and platforms is ensured.

What are the types of End-to-End testing?

Horizontal End to end testing: Horizontal end-to-end testing is performed horizontally over a wide range of applications and occurs in a single ERP app. It ensures the application user can navigate across different menus and pages and find the desired functions. This form of testing also helps to find out errors that may create a barrier for users to perform specific functions.

Vertical End to end testing: Vertical end-to-end testing is performed in layers. Testers execute the test cases in a hierarchical manner that ensures all the components of the application are tested end to end. Vertical testing validates critical functions of the application which users may not test.

System Testing vs End-to-End Testing – Key Differences

System testing and end-to-end testing go hand-in-hand and are sometimes considered the same as both are performed to test the application behaviour. However, both vary in the purpose and metrics of testing.

The given table depicts the key differences between system and end-to-end testing:

System Testing	End-to-end Testing
In system testing, the entire software or application is tested at a time.	In end-to-end testing, the behavioral flow of the application is tested.
Validates specific software systems.	Validates the software system as well as other connected systems.
Checks the application functionality.	Checks the user flow from end to end.
Tests the app according to the pre-defined specifications.	Tests all interfaces of application.
Testers may not know the interconnected systems	Testers need to know about the interconnected systems.
It’s carried out after integration testing.	It’s carried out after system testing.
Can be performed both manually and automated.	Usually performed manually.
A superset of end to end testing.	A subset of system testing.

System Testing vs End to End Testing: Which is better?

There is no denying that system testing and end-to-end testing are often considered the same, but as we saw above, that is not the case. Both types of testing are different and cater to dedicated test coverage.

While testers perform end-to-end testing to validate the application flow from the beginning to the end by incorporating the dependencies, system testing validates the same features over different responses.

As it is clearly described above, neither of the two testing processes is better than the other. Both testing methodologies are performed to validate different functions and features of the application and yield different test results.

The argument as to which system and end to testing is best comes from the misconception that both methods are alike. It is recommended not to prioritize system testing over end-to-end testing or vice versa, as it may lead to overlooking the critical features of the application.

Summary

When performing system testing, testers should act like real users and validate the integration of each functionality. In the case of end-to-end testing, testers should analyze the process flows of the application.

Both testing types have a critical role to play in ensuring high-quality application releases while helping testers uncover crucial bugs and errors in different categories.

Frequently Asked Questions

What is an example of system testing?

Let’s take an example of a mobile application that provides a cab booking facility. It will feature different functions such as cab scheduling, geo-tracking, different modes of payment, driver details, and so on.

• All these features should be tested under the unit testing process.


• Once all the app modules are verified for functionality, these are tested together to ensure seamless operations via integration testing.


• System testing will finally validate the customer requirements such as: – Is the customer able to find and book a cab? – Is the customer able to pay using their preferred mode of payment methods?

Validating such user scenarios is covered in System testing.

What is an example of end-to-end testing?

The following is an example of end-to-end testing for a voice-recording application:

Ideal functions

• Record audio from a second (minimum) to five minutes (maximum)


• Download audio files.


• Share audio files via email and other sharing apps.

User conditions

• iPhone with email app
• iPhone with Outlook app
• Android with Gmail app
• Android with Outlook app

Test case

• Open the application.
• Start recording for a second.
• Download the audio file.
• Start recording again for five minutes.
• Download the audio file.
• Check the audio files in phone storage.
• Share audio files to the email account.
• Close the recording app.

What is another name for end-to-end testing?

Another name for end-to-end testing is chain testing. End-to-end testing is performed after functional and system testing. It imitates conditions similar to the real world by using a real-world QA environment and test data.

Why is system testing done?

• During a Software Development Life Cycle, the system is tested as a whole through system testing.


• In this phase, testers validate if the system or application under test meets the functional and business requirements.


• The application undergoes testing in an environment that is similar to the production environment where the application is intended to be finally deployed.