[CI] Code coverage reports
Previous efforts to gather and publish C++ code coverage using the free
service provided by coveralls.io have stalled (see ARROW-27).
I went ahead and experimented with another free service, codecov.io. I
got it to work with our C++ and Rust code bases. An example report can
be seen here:
The proposed changes are in PR #2023.
The two platforms, codecov.io and coveralls.io, seem largely similar:
they provide free hosting for code coverage reports, support a range of
programming languages and code coverage formats, and display compute
coverage changes accross repository commits. I find codecov.io slightly
more readable but that's just a personal opinion.
Do people or the Apache project have a strong preference for one of
those two services?