Automatic test coverage reports with coveralls.

[jimhester]

You will have to enable this repo on coveralls at https://coveralls.io/repos/new before merging this pull request for the report to work the first time.

[yihui]

Thanks! This is very interesting and useful. One question, though: since I do not use testthat (I use my own tiny package testit instead), does covr still work in that case? Or actually, does covr really have to "endorse" a specific testing framework? I have noticed covr a while ago, and I have been waiting for a better documentation (e.g. a package vignette) about how it actually works. Otherwise it is completely magic to me, and I'm not sure if it really works in my case. I tried to read the source code, but it does not seem to be something that I can understand in a few minutes :)

[yihui]

BTW, while I'm reading the help pages, I have a humble suggestion that you export as fewer functions as possible, e.g. I do not quite see the value of exporting clear_counters, count, key, and so on. Two reasons: 1. avoid names clashing with other packages; 2. exported objects are kind of like promises to users that these are mature objects to use and won't change much in the future.

[yihui]

Perhaps surprising to you again, I do not use travis-tool.sh, either, since I think it is trivially easy to set it up by myself, and I'm more familiar and comfortable with apt-get :)

[jimhester]

covr just sources the files in your tests, inst/tests directories, so it should work with any testing framework. I verified it does work with testit and the knitr tests before submitting this pull request.

re: exporting functions that is a fair criticism, I un-exported them at r-lib/covr@e77b2a5 , thank you for the suggestion and I agree with your reasoning.

I had previously seen that you did not use r-travis, but forgot about that fact when I was submitting this pull request, my apologies, I modified the yaml with r-lib/devtools#681 and clearly did not examine the file before submitting, my apologies.

[yihui]

No no I was not criticizing you exporting functions. It was just a suggestion :)

Now it seems everything is good. Could you squash your three commits into one? e.g. git reset --soft HEAD~3 (assuming you are on the covr branch) then commit and force push (https://github.com/yihui/knitr/blob/master/CONTRIBUTING.md)

BTW, I'd still love to see a vignette describing how covr works under the hood. I understand you may not want to spend time on it, but I'm very interested in your magic 👍

[jimhester]

Ok I squashed everything into one commit! Let me know if there is anything else you need.

I think your vignette suggestion is a good one, a couple other people have wanted to know how it works as well. I will put one together soon.

[yihui]

Excellent. Thanks!