What does "test coverage" indicate?

Test coverage indicates the extent to which source code is tested by test cases. It is a critical metric in software testing that helps assess how much of the codebase is being exercised by the automated tests. This can be measured in various ways, including statement coverage (how many lines of code have been executed), branch coverage (how many branches in the control flow of the code have been tested), and function coverage (how many functions have been called during testing).

Having high test coverage suggests that the majority of the code is being validated through tests, which can lead to the identification of defects and improve overall software reliability. It serves as an indicator that developers and testers are actively involved in ensuring the application behaves as expected under various scenarios.

In contrast, the other options do not accurately reflect the concept of test coverage. The number of bugs found during testing relates to fault detection, the average time taken for testing pertains to efficiency, and the quality of test cases written touches on the effectiveness of tests but does not measure how much of the source code is covered by those tests.