Unit Testing: Unit Testing is done to check whether the individual modules of the source code are working properly. i.e Testing each and every unit of the application separately by the developer in developers environment.

Interface Testing: Interface Testing is done to check whether the individual modules are communicating properly one among other as per the specifications.

Interface Testing is mostly used in testing the user interface of GUI applications.

Integration Testing: Integration Testing is done to check the connectivity by combining all the individual modules together and test the functionality.

The types of Integration Testing are,

1) Big Bang Integration Testing

In Big Bang Integration Testing, the individual modules are not integrated until all the modules are ready. Then they will run to check whether it is performing well.

In this type of testing, some disadvantages might occur like,

Defects can be found at the later stage.

It would be difficult to find out whether the defect arouse in Interface or in module.

2) Top Down Integration Testing

In Top Down Integration Testing, the high level modules are integrated and tested first. i.e Testing from main module to sub module. In this type of testing, Stubs are used as temporary module if a module is not ready for integration testing.

3) Bottom Up Integration Testing

In Bottom Up Integration Testing, the low level modules are integrated and tested first i.e Testing from sub module to main module. Same like Stubs, here drivers are used as a temporary module for integration testing.

1. Black box testing
2. White box testing
3. Gray box testing

Black box testing – Testing the application without any knowledge of the internal design/code, Tests are based on requirements and functionality.

White box testing –Testing the internal logic of the application code, Tests are based on coverage of code statements, branches, paths, conditions.

Unit testing - the most 'micro' scale of testing; to test particular functions or code modules. Typically done by the programmers and not by testers, as it requires detailed knowledge of the internal program design and code. Not always easily done unless the application has a well-designed architecture with tight code; may require developing test driver modules or test harnesses.

Incremental integration testing - continuous testing of an application as new functionality is added; requires that various aspects of an application's functionality be independent enough to work separately before all parts of the program are completed, or that test drivers be developed as needed; done by programmers or by testers.

Integration testing - testing of combined parts of an application to determine if they function together correctly. The 'parts' can be code modules, individual applications, client and server applications on a network, etc. This type of testing is especially relevant to client/server and distributed systems.

Functional testing - black-box type testing geared to functional requirements of an application; this type of testing should be done by testers. This doesn't mean that the programmers shouldn't check that their code works before releasing it (which of course applies to any stage of testing.)

System testing - black-box type testing that is based on overall requirements specifications; covers all combined parts of a system.

End-to-end testing - similar to system testing; the 'macro' end of the test scale; involves testing of a complete application environment in a situation that mimics real-world use, such as interacting with a database, using network communications, or interacting with other hardware, applications, or systems if appropriate.

Sanity testing or smoke testing - typically an initial testing effort to determine if a new software version is performing well enough to accept it for a major testing effort. For example, if the new software is crashing systems every 5 minutes, bogging down systems to a crawl, or corrupting databases, the software may not be in a 'sane' enough condition to warrant further testing in its current state.

Regression testing is done after fixes or modifications of the software or its environment.(on modified build) It can be difficult to determine how much re-testing is needed, especially near the end of the development cycle. Automated testing tools can be especially useful for this type of testing.

User Acceptance testing - final testing based on specifications of the end-user or customer, or based on use by end-users/customers over some limited period of time.

Load testing - testing an application under heavy loads, such as testing of a web site under a range of loads to determine at what point the system's response time degrades or fails.

Stress testing - term often used interchangeably with 'load' and 'performance' testing. Also used to describe such tests as system functional testing while under unusually heavy loads, heavy repetition of certain actions or inputs, input of large numerical values, large complex queries to a database system, etc.

Performance testing - term often used interchangeably with 'stress' and 'load' testing. Ideally 'performance' testing (and any other 'type' of testing) is defined in requirements documentation or QA or Test Plans.

Usability testing - testing for 'user-friendliness' of the application. Clearly this is subjective, and will depend on the targeted end-user or customer. User interviews, surveys, video recording of user sessions, and other techniques can be used. Programmers and testers are usually not appropriate as usability testers.

Install/uninstall testing - testing of full, partial, or upgrade install/uninstall processes.

Recovery testing - testing how well a system recovers from crashes, hardware failures, or other catastrophic problems.

Security testing - testing how well the system protects against unauthorized internal or external access, willful damage, etc; may require sophisticated testing techniques.

Compatibility testing - testing how well software performs in a particular hardware/ Software/operating system/network/etc. environment

Exploratory testing - often taken to mean a creative, informal software test that is not based on formal test plans or test cases; testers may be learning the software as they test it.

Ad-hoc testing - similar to exploratory testing, but often taken to mean that the testers have significant understanding of the software before testing it.

Comparison testing - comparing software weaknesses and strengths to competing products

Mutation testing - a method for determining if a set of test data or test cases is useful, by deliberately introducing various code changes ('bugs') and retesting with the original test data/cases to determine if the 'bugs' are detected. Proper implementation requires large computational resources.

It is a process used to look out whether the security features of a system are implemented as designed and also whether they are adequate for a proposed application environment. This process involves functional testing, penetration testing and verification.

Installation testing is done to verify whether the hardware and software are installed and configured properly. This will ensure that all the system components were used during the testing process. This Installation testing will look out the testing for a high volume data, error messages as well as security testing.