[test runner] code coverage does not include untested files

[jmcgavin]

The includes property of the coverageConfig object does not include untested files in the code coverage. Only files visited during tests are included in the coverage.

I think having the option to include the entire codebase in the code coverage output is a good idea. Either through the includes property or the addition of an all property like the --all flag that can be used with istanbul/nyc or c8.

[jmcgavin]

The @web/test-runner-coverage-v8 package uses the v8-to-istanbul lib which initializes all to false.

[jmcgavin]

Relates to #1873

[u-b-i-p-i-x-e-l-s]

@LarsDenBakker would love to have your feedback on this. 😃

[LarsDenBakker]

I'm not sure the "all" flag would change anything here. Did anyone test this? I think we need to see all the files in the browser to make them show up in the coverage.

[electrovir]

This may be overkill but here's a workaround:

1. before running web-test-runner, run a new script that finds all your files
2. using that script, generate a new TS/JS file that imports all the found file paths from step 1
3. include that new file in the test files that web-test-runner executes
4. now all your files are included in the coverage report because the browser imported them all!

[mohamedmansour]

This may be overkill but here's a workaround:

1. before running web-test-runner, run a new script that finds all your files

2. using that script, generate a new TS/JS file that imports all the found file paths from step 1

3. include that new file in the test files that web-test-runner executes

4. now all your files are included in the coverage report because the browser imported them all!

Another approach instead of creating a new test file is to add it to Istanbul reporter as 0 coverage for all files found then merge the coverage data found.