What is Gray Box Testing

Question:
What is Gray Box Testing? Where & how Gray Testing is used?

Posted by ashu_akl

Answer:
Let's begin with the most basic forms of testing: white box, or glass box
versus black box testing: I will quote from Testing Computer Software:
Second Edition (1993) Cem Kaner, Jack Falk, Hung Quoc Nguyen.

Glass box testing is distinguished from black box testing, in which the program is treated as a black box. You can't see into it. The tester (or programmer) feeds it input data, observes output data, but does not know, or pretends not to know, how the program works. The test designer looks for interesting input data and conditions that might lead to interesting outputs. Input data are "interesting" representatives of a class of possible inputs if they are the ones most likely to expose an error in the program.

In contrast, in glass box testing, the programmer uses her understanding and access to the source code to develop test cases.

At this point, on page 41of Testing Computer Software, they go into explaining the benefits of white box testing. They also spend the next few pages going over the concepts of white box testing.

In recent years I have also heard of gray box testing. In this form of testing, the tester has access to some of the inner workings of the system, usually the database, but not the code.

White box testers have access to the code, but even a black box tester canknow the branches of code--the rules within the code that cause operations to fork. A white box tester generally uses the code, and the ability to create drivers and stubs to test the code directly. They do not rely on the UI to do it.

The typical gray box tester is permitted to set up his testing environment,
like seeding a database, and can view the state of the product after their
actions, like performing a SQL query on the database to be certain of the
values of columns. It is used almost exclusively of client-server testers or
others who use a database as a repository of information, but can also apply to a tester who has to manipulate XML files (DTD or an actual XML file) orconfiguration files directly.

The true black box tester looks only at the GUI and can not touch intermediate files, registry entries, databases, etc., nor are they permitted to see the results their actions have wrought, other than through the UI. They are, therefore, only permitted to use the UI to do their testing.

Posted by Walter Görlitz