How is coverage expressed in testing contexts?

Coverage in testing contexts is commonly expressed as a percentage of test cases executed. This approach reflects how many of the designed test cases have been run against the software under test, providing insight into the breadth of testing that has been performed. By measuring coverage in this manner, testers can evaluate whether sufficient testing has occurred and identify any areas that may require further testing to ensure that the product has been thoroughly vetted.

This measurement is critical for assessing the thoroughness of testing efforts, as it allows teams to understand which aspects of the functionality have been validated and which remain untested. Focusing on the execution of test cases helps in managing testing progress and addressing areas that may need additional attention, thus supporting overall quality assurance objectives in a structured manner.

In contrast, coverage expressed as a ratio of successful tests or as a number of requirements tested does not provide a complete picture of how many tests were actually executed compared to those that were planned. Similarly, coverage expressed as a percentage of covered requirements does not take into account whether all test cases associated with those requirements were completed. This makes evaluating the effectiveness and thoroughness of the testing process more difficult.