Levels of Testing

Black-box Testing - Tests are based on requirements and functionality and not on knowledge of internal design or code.

White-box Testing - Based on knowledge of the internal logic of an application's code. Tests are based on coverage of code statements, branches, paths and conditions.

Unit Testing - The most 'micro' scale of testing which tests particular functions or code modules. Typically done by the programmer and not by testers, as it requires detailed knowledge of the internal program design and code.

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.

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

Regression Testing - Re-testing after fixes or modifications of the software/ environment. 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.

Acceptance Testing - Final testing based on specifications of the end-user or customer, or based on use by end-users/customers over a limited period.

Load Testing - testing an application under heavy loads, such as testing of a website under a range of loads to determine at what point the system's response time degrades or fails. Acceptance Testing helps determine if the software is satisfactory to a customer.

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'. 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.

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 environment (hardware/software/operating system/network/etc).

Comparison Testing - Comparing software weaknesses and strengths to competing products.

Alpha Testing - Testing of an application when development is near completion, minor design changes may still be made as a result of such testing. Typically done by end-users or others, not by programmers or testers.

Beta Testing - Testing when development and testing are essentially completed and final bugs and problems need to be found before final release. Typically done by end-users or others not by programmers or testers.