Different Levels of Testing in Software Testing

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What are the Levels of Software Testing?

In this blog,we are going to understand the various levels of software testing

In Software Testing,we have four different levels of testing,which are as mentioned below:

  1. Unit Testing
  2. Integration Testing
  3. System Testing
  4. Acceptance Testing

Levels of software testing

Level 1:Unit Testing

Unit Testing is the first level of software testing,which is used to test the software module is satisfying the given requirement or not.Unit testing is done at the code level,where each component is tested individually.The first level of testing involves analyzing each unit or an individual component of the software application.This type of testing is done by the developer.

Level 2:Integration Testing

Integration testing process comes after Unit testing.It is the second level of software testing.The main aim of Integration testing is used to test the data flow from one module to other module.In other words,Integration testing is a testing technique where two or more independent modules are tested together.This kind of testing is performed by testers.

Integration testing is again classified into four types:

i) Big-Bang Integration Testing
ii) Bottom-Up Integration Testing
iii) Top-Down Integration Testing
iv) Mixed Integration Testing/Sandwiched integration testing.

Level 3:System Testing

The third level of software testing is System testing,which is used to test the software functional and non-functional requirement.To check the end-to-end flow of an application as a end user is known as System testing.It is done on a testing server,which is similar to production server.It helps to validate the requirements and ensure the system meets the user needs.

System testing is also performed by testers.

Level 4:Acceptance Testing

Acceptance testing is the last phase of software testing performed after system testing and before making the system available for actual use.Once the application is bug free,we handover it to the customer,no customer accept the application blindly before using it.Hence they do one round of testing for their satisfaction,which is known as user acceptance testing.

User acceptance testing is done by the customer before accepting the final product at UAT server.

The main purpose of this test is to evaluate the system’s compliance with the business requirements and verify the product has met the required criteria for delivery to end users.Once the client completes acceptance testing the product goes to production where users can use the final application.


  1. There are four levels of software testing that an application undergoes.
  2. Unit testing is done by the developer.It ensures the developed modules are defect-free.
  3. Integration and System testing is done by tester.In integration testing,different modules are tested together whereas in System testing the entire application is verified.
  4. Acceptance testing is done by the customer.Once acceptance testing is done users can use the final application.

Thank You
Nikhila Bejjala
Helical IT Solutions

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