Code Coverage

Code coverage indicates the percentage of code tested by automated tests.

Code Coverage Percentage = (Number of lines of code executed by a testing algorithm / Total number of lines of code) * 100.

If you have a large code coverage percentage, that means you have a large amount of your source code executed during tests. As a result, your chances of having undetected software bugs is lower than if you had a lower code coverage percentage. Having 100% code coverage, however, does not mean that you will not have undected software bugs. The code coverage simply measures the quanity of code coverage and not the quality of the tests. To provide good testing coverage, you should continually look to improve the quality of your tests and not just the quality.

Increases in the amount of code coverage combined with defect detection metrics can help you measure the quality of your tests and the quality of your code, even if code coverage alone is not an adequate quality metric.