Feature request: add ability to merge .info files together

[f18m]

Hi,
it would be really nice to have in fastcov the same option that lcov provides, i.e. the --add-tracefile option which allows you to merge together .lcov files (or .info files in fastcov case).
This allows to merge contributes from different runs of the same source tree from e.g. different containers...

[RPGillespie6]

Are you using genhtml? If so, you can just pass them all and it will handle it correctly :

$ genhtml coverage1.info coverage2.info coverage3.info -o html_report

That said, I'll look into seeing how hard it would be to add that feature into fastcov itself.

Would it be acceptable to merge fastcov json files and then spit out lcov format at the very end? Currently fastcov only generates lcov files, so I would have to add the ability to parse lcov files if that is a requirement. However, it would be fairly trivial to be able to merge fastcov json files (since it is just json) and then spit out lcov format for the final report:

$ fastcov ... -o coverage1.json
$ fastcov ... -o coverage2.json
$ fastcov ... -o coverage3.json
...
$ fastcov --add-tracefile coverage1.json coverage2.json coverage3.json ... --lcov -o coverage_final.info