The term test coverage used in the context of programming / software engineering, refers to measuring how much a software program has been exercised by tests. Coverage is a means of determining the rigour with which the question underlying the test has been answered. There are many kinds of test coverage:
code coverage feature coverage, scenario coverage, screen item coverage model coverage. Each of these coverage types assumes that some kind of baseline exists which defines the system under test. The number of types of test coverage therefore varies as the number of ways of defining the system.