Levels of Testing(Stages of Testing)

1) Component Testing/Unit Testing

2) Integration Testing

3) System Testing

4) Acceptance Testing

5) Functional Testing

1. Component Testing/Unit Testing

• Component or unit is the smallest testable portion of the system or application which can be tested and executed
• This testing helps to test each and every model separately. It checks that components are fulfil the functionality or not
• This kind of testing is perform by developer

2. Integration Testing

• This kind of testing perform by tester.
• This kind of testing is used to combine different software modules as a group to ensure that integrated software is ready for the system testing
• We check data flow from one module to another module.

3. System Testing

• System testing perform on the complete integration testing
• It evaluates both functional and non-functional testing
• It also involves load ,performance, reliability and security testing

4. Acceptance Testing 

• This kind of testing is done by user or customer
• However, shake holders can be involved in this process

5. Functionality Testing

• Check each and every functionality of an application

• This is used to check if your product is as per the specifications you intended for it as well as the functional requirements you charted out for it in your developmental documentation.