Gray box testing is a type of professional testing often used for computer software, which combines certain aspects of black box testing and white box testing. The general idea is to combine these two other types to utilize the strengths of each, while minimizing their limitations or weaknesses. Gray box testing basically consists of professional testing in which the testers understand some of the ways in which the software works, but they do not understand everything about it.
When developing and testing computer software, there are two common models of testing often utilized. These are black box testing and white box testing, and gray box testing is basically a combination of both. Black box testing consists of testing in which the testers do not understand or have access to the code that runs the software. For example, someone may utilize black box testing to allow an outside company develop software to run with a computer operating system (OS) without giving the company the source code for the OS.
This type of testing is often used by many different software companies, and can be used for both in-house and outside testing. One of the biggest weaknesses of this type of testing, however, is that the limited knowledge of the testers may potentially hamper their testing. This will often require the results to be analyzed by a third party who understands both the tests being run and the code behind the software being tested. Gray box testing seeks to alleviate some of these problems by combining this type of testing with certain elements of white box testing.
White box testing consists of software testing done by people who fully understand the software being tested and have access to the source code for the software. This is often done in-house at a software developer to ensure the program runs properly and to allow the testers to directly interact with the code behind the program. There are potential security issues with this type of testing, however, and so gray box testing is often used to combine both types in ways that are both productive and secure.
In gray box testing, the testers understand certain aspects of the software being used and may be able to see some portions of the source code but not all of it. This allows the testers to more fully interact with and understand the program they are testing than black box testing allows, but without the full access and security issues that can arise from white box testing. Someone performing gray box testing on software for a new OS, for example, may be able to see code for aspects of the OS relevant to his or her testing of the program, but not all of the source code.