Which term refers to the percentage of decision outcomes that have been exercised by a test suite?

The correct answer is "Decision coverage," which refers specifically to the metric that measures the percentage of decision outcomes (true or false) that have been tested within a software application. In the context of testing, decisions typically come from conditional statements, such as if-else statements or switch-case constructs. By using decision coverage as a metric, testers can ensure that they have evaluated all the logical paths in the code, providing a clear picture of the thoroughness of their tests concerning the decisions made in the code.

Decision coverage is crucial because it helps identify potential defects that may arise from different logical outcomes. A test suite that achieves high decision coverage indicates that various scenarios have been validated, which reduces the risk of runtime errors caused by untested logic.

In contrast, the other terms relate to different aspects of code testing. Code coverage measures the overall lines of code that have been executed during the tests but does not specifically address the decisions within those lines. Branch coverage is similar but focuses on the execution of all branches within control structures, ensuring every route through those structures is tested. Test coverage, on the other hand, is a more general term that encompasses various testing metrics, including functional tests, but does not specifically target decision outcomes.