Acceptance Testing vs System Testing: Why do we need them?

The Software Development Life Cycle (SDLC) has multiple stages, which include some testing phases. System testing and acceptance testing are integral parts of the overall testing lifecycle.

In system testing, we test the system as a whole. We integrate all the modules and components and verify if the system meets the expectations or not. Once we have successfully tested the system, the entire application can be handed over to the users to check for its acceptability. We call this acceptance testing.

Hence, first, we do the system testing on the application and then send it for acceptance testing to the users to determine the Go/No-Go for delivery. Therefore, both testing types are necessary in order to achieve a successful release of the application.

In this article, let’s understand the differences between system and acceptance testing and when to use them for your application.

Acceptance Testing vs System Testing – Overview

What is Acceptance Testing?

In the acceptance testing phase, we test a system for its acceptability from the user’s perspective. The main goal of acceptance testing is to evaluate the system’s compliance with the business requirements. Based on this, we can assess whether the system is acceptable for delivery/release.

The users or clients carry out acceptance testing in a UAT environment. They validate the new features and once you get a GO, you can release the product. It is a form of black-box testing because the users who test the application do not know about the internal implementation of the code.

We usually carry out acceptance tests after system testing. Although similar, business users demand acceptance testing before releasing the product. This is to verify whether the product meets the acceptance criteria and whether the functionalities work as expected.

What is System Testing?

In system testing, we test and validate the fully integrated hardware and software system. We verify whether the system as a whole meets the specified requirements. We usually build an application by integrating a lot of subsystems. The main goal of a system test is to test the end-to-end system specifications.

System testing is also black-box testing because it is done from a user’s perspective. We test it using a black-box strategy where we provide the input to the system and verify the output. The tester does not need to know the code design of the application. The main focus areas of a system test are external interfaces, performance, stability, recovery, stress/load, and smooth interaction with different parts of the system.

We perform system tests in a dedicated production-like environment. They help us to minimize the troubleshooting and support calls after deployment. Also, in this case, we test both the business requirements and application architecture.

Acceptance Testing vs System Testing: Key Differences

Here get the key difference between acceptance testing and system testing below.

Acceptance Testing	System Testing
We perform acceptance testing to check if the product meets the requirements of use/business	We perform system testing to test the software as a whole.A complete end to end test is performed to check if all the features work as expected
It includes only functional testing and is performed by end-users or stakeholders	It includes both functional and non-functional testing.The tests are performed by a team of testers.
We use real data from production to perform acceptance testing	Mocked or test data is used to perform system testing
It verifies the business requirement and what the customer wants	It tests the performance, regression,reliability, compatibility,security and other such aspects of the product.
It is a combination of alpha and beta testing	It is a combination of system and integration testing
The product is considered as a failure if a defect or bug is found	Any bugs if found are fixed and retesting is done.
Here, we only check if the new product meets specified requirements	Here, we tests the system’s integrity and whether it interacts well with subsystems and external applications.

Conclusion

To conclude, both acceptance and system testing plays a huge role in ensuring the quality of the product before being released. The primary focus of system testing is to test the overall integrated system and other aspects like performance, scalability, security, etc. On the other hand, the business or end-users perform acceptance testing to validate if the product meets the specified requirements.

Both system and acceptance testing are types of black-box testing. System testing is performed by a team of testers who are given input and expected output. They don’t require any knowledge of the implementation.

When these tests are performed successfully before the release of the product, the chances of a bug being found in production reduce multi-folds. Hence, it’s imperative to perform end-to-end testing like system testing and a test from the business perspective.

Frequently Asked Questions

Who performs system testing and acceptance testing?

System testing is performed by a team of specialized testers in an environment similar to production. They carry out a series of tests to validate the performance, security, reliability, scalability, and other aspects of the system that the unit and integration tests do not cover. On the other hand, acceptance tests are usually carried out by business users or end-users. They do this test to ensure that the final product meets the specified business requirements.

What is the similarity between system testing and user acceptance testing?

System and user acceptance testing are dynamic testing methods used to verify all the requirements specified for the software or the application. They help us validate the overall stability of the system and find out bugs that unit or integration testing methods cannot detect. They are both black-box testing methods because they don’t require any code implementation knowledge.

What is the difference between user acceptance testing and system Integration testing?

User acceptance testing (UAT) simulates real users testing the system for usability and business needs, while system integration testing validates how different parts of the system work together technically. 

UAT checks if the system works for users, while integration testing checks if the system works as a whole.

Is acceptance testing part of system testing?

Acceptance testing is typically the final phase of system testing, focusing on validating whether the system meets the specified requirements and is ready for deployment.

What is the difference between acceptance testing and end-to-end testing?

Acceptance testing verifies whether the system meets business requirements and user needs. In contrast, end-to-end testing examines the entire system workflow, including integration with external systems, to ensure seamless functionality across all components.

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