show code coverage with Codecov.io

[wilzbach]

Hi all, the idea for this automation is simple, let's ensure (1) that no PR decreases the code coverage, (2) help reviewers judging code coverage improvements PRS, (3) provide simple tools for contributors to see which parts are uncovered.

You can preview this here.

That being said, this won't be perfect in the near future as Travis can only run Linux and Mac OS builds, so special versioned paths will not be treated right. The idea here is to get an easy 90% solution that already helps reviewers in most cases (=a lot better than 0%). In the future we might add Codecov reporting to the AutoTester.

Now to this PR:

1. Thanks to the help from @stevepeak, Codecov.io is able to recognize the code coverage output from our builds
2. I haven't figured out yet how I can get the test runner to report the test coverage, for now I settled with
   make -f posix.mak std.test etc.test
3. I ran into a couple of issues during my first attempt, so don't merge yet. At the moment I was lazy and just commented them out, but I/we should definitely investigate the root cause of them:

• entropy in std.numeric (and thus schwarzSort in std.algorithm.sorting)
• utf-16le in std.encoding
• iso-8859-1 not recognized for std.net.curl

4. As the newest druntime and dmd are needed, we now have to move phobos in its own folder and then clone the other repos. It makes the Travis script a bit ugly, better ideas are of course welcome.

(if everything goes well, CodeCov should comment on this PR)

[codecov-io]

Current coverage is 88.68% (diff: 100%)

No coverage report found for master at f9dd0f8.

Powered by Codecov. Last update f9dd0f8...d8c181b

[WalterBright]

why turn off @safe?

[stevepeak]

@wilzbach Nice job :) Let me know if you have any questions about Codecov configuration.

[wilzbach]

Encoding's aren't registered properly for single tests - see e.g. #4493 and the reported bug for more infos.

[wilzbach]

Travis is passing finally 🎉, so this experiment is ready.

As mentioned earlier there are some weird bootstrapping issues with std.encoding, but they are reported and being worked on. Thus these modules are excluded currently from the coverage report.

You can preview the automatic coverage report here.

In case you are unfamiliar with CodeCov, it's a service that processes coverage reports and will hopefully help us to spot coverage regression and judge coverage improvements.

The behavior of CodeCov is highly configurable, so if anything annoys or will annoy you, we most likely will find a solution ;-)