This is only relevant to people working at Dyalog Ltd.
Checking for code coverage reports is a very important part. Though not very reliable to measure all cases have been tested, code coverage reports give us an assurance that there are no codepaths left unturned with the tests. It helps us remove dead code and refactor code. It is a very helpful testing and refactoring technique.
Find the documentation at on how to generate a code coverage report with Dyalog APL: https://wiki.bramley.dyalog.com/index.php/Code_coverage_reports