A measure of the proportion of a program exercised by a test suite, usually expressed as a percentage. This will typically involve collecting information about which parts of a program are actually executed when running the test suite in order to identify which branches of {conditional statements} which have been taken. The most basic level of test coverage is {code coverage testing} and the most methodical is {path coverage testing}. Some intermediate levels of test coverage exist, but are rarely used. The standard Unix tool for measuring test coverage is tcov, which annotates C or Fortran source with the results of a test coverage analysis. GCT is a GNU equivalent. (2001-05-20)