Software release life cycle - stages of development

levels of testing
In software development life cycle models there are defined phases like:
- requirement gathering and analysis,
- design,
- coding or implementation,
- testing
- deployment.

Each phase goes through the testing. Hence there are various levels of testing. The various levels of testing are:

1. Unit testing
It is basically done by the developers-programmers to make sure that their code is working fine and meet the defined specifications. They test their piece of code which they have written like classes, functions, interfaces and procedures. The main aim of this endeavor is to determine whether the application functions as designed. In this phase, a unit can refer to a function, individual program or even a procedure, and a White-box Testing method is usually used to get the job done.

2. Component testing
It is also called as module testing. The basic difference between the unit testing and component testing is in unit testing the developers test their piece of code but in component testing the whole component is tested. Both the modules are developed separately and when they are tested all together we call this as a component or module testing.

3. Integration testing
Integration testing is done when two modules are integrated, in order to test the behaviour and functionality of both the modules after integration. Below are few types of integration testing:
Big bang integration testing
Top down
Bottom up
Functional incremental

4. Component integration testing
In the example above when both the modules or components are integrated then the testing done is called as Component integration testing. This testing is basically done to ensure that the code should not break after integrating the two modules.

5. System integration testing
System integration testing (SIT) is a testing where testers basically test that in the same environment all the related systems should maintain data integrity and can operate in coordination with other systems.

6. System testing
In system testing the testers basically test the compatibility of the application with the system.

7. Acceptance testing
Acceptance testing are basically done to ensure that the requirements of the specification are met.

8. Alpha testing
Alpha testing is done at the producers site. It is done at the end of the development process

9. Beta testing
Beta testing is done at the customers site. It is done just before the launch of the product.