System Testing

In this article, we are going to learn about System testing in detail. But before that, we need to learn about the different software testing levels. The software testing hierarchy consists of 4 steps starting from unit testing then integration testing, moving upwards to system testing, and lastly user acceptance testing. 

Let us understand each step briefly. 

Unit testing – During the first phase of SDLC, when the parts are being developed unit testing is performed. This is done on small blocks of the application. It is usually done by the developer/ programmer who has written the codes.

Integration testing – Several modules interact with one another and together make a whole software. In integration testing, the integrated modules are tested.

System testing – Then comes the system testing. Once the whole system is put together and integrated into one, the system is checked as a whole. The purpose is to check the system from the user’s point of view. 

Acceptance testing – Acceptance testing is the final level of software testing where the system is tested for compliance with its business requirements.

Let’s understand System testing in detail now.

What is System Testing?

System testing is a type of testing where the application as a whole is tested for its compliance with functional and non-functional requirements. It is carried out by the QA team after the completion of integration testing and before the final acceptance testing.

Since in system testing the whole system is tested end to end and the knowledge of coding or internal architecture is not required. Hence, system testing comes under Black-box Testing.

Why do we need System Testing?

  • The system is tested as a whole in this phase of testing. Even after successful unit and integration testing, many complex scenarios may have issues undiscovered by earlier testing phases. System testing helps in uncovering those defects.

  • Both the functional as well as non-functional requirements are tested for the whole system are tested for the first time in this phase.

  • The testing is carried on the product and environment that closely matches the final product and production environment. Hence, successful system testing brings a sense of confidence in the final delivered product.

  • The system is evaluated on the basis of the user’s point of view, which is an important way to understand the end-users requirement. After all, it is them that are going to use the system ultimately.

Types of System Testing

As stated earlier, in system testing both the functional and non-functional requirements of the system are evaluated. Hence, system testing involves different types of testing techniques that evaluate the whole system and its various attributes.

The different types of system testing are – Functional testing, Performance testing, Usability testing, Reliability testing, Security testing, Scalability testing, Installation testing, etc.

System Testing Process

Now that we know what system testing is let us understand what steps are involved to execute the system testing process.

  1. Setting test environment – the first step is to create a test environment that matches the real-time scenario for quality testing.

  2. Test cases – the next step is to create test cases for an exhaustive testing process.

  3. Test data – random test data input should be collected for the testing process.

  4. Execution – the test cases with the test data should be executed.

  5. Bugs/defects detection – in this detection for detects is started and are reported if found any.

  6. Regression testing – this step is done to check the side effects of the whole testing process.

  7. Defects logging – all the defects are logged into the file and sent to the developers’ team for a fix.

  8. Restest – once the defects are fixed the whole system is checked again till successful testing is not achieved.


System testing is an important step in the testing cycle. Until and unless the system is tested as a whole we cannot judge the application’s efficiency completely. Therefore, it is important to test the system as a whole before actually deploying it into the market.

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