The objective of domain testing is to select test data to detect control flow errors and to characterize the extent to which these errors can be detected. As such, it is clearly a white-box approach, representing an example of structural testing. In terms of the software life cycle, domain testing was originally devised to be applied during unit testing; however, it was recommended that it could be applied in testing specifications as well.

The predicates in a program can be viewed as essentially acting as constraints in the input space of that program. For each path through the program, these predicate constraints will define and bound the set of input data points which will all follow that path; these points then constitute the corresponding input space domain. Since domain testing will address the testing of the boundaries of that domain, this is the reason this testing technique is called domain testing. Before domain testing is discussed further, the concepts of predicate interpretation and input space structure will be presented in greater detail.