Local coverage reporting

[springmeyer]

Context

• Adding tests as you develop code is critical.
• Being able to see the coverage of those tests is instrumental to knowing what tests are missing and to feeling motivated to write tests.
• Being able to get quick feedback on coverage locally (rather than waiting for travis + codecov) can be a huge productivity boost for writing tests to achieve more coverage

Solution

https://github.com/mapbox/cpp#code-coverage describes how to use clang++ and llvm-cov to instrument the code and view code coverage locally.

For the best results this requires:

• llvm-cov 4.0.0
• the same version of clang++ as llvm-cov to compile the code (so also clang++ 4.0.0)

https://github.com/mapbox/node-cpp-skel/blob/master/scripts/coverage.sh is an example of scripting the recompile of code and automatic reporting of coverage.

[springmeyer]

This depends on #12 being in place, since having the environment from setup.sh available greatly simplifies the coverage.sh script.

[springmeyer]

Solved by #27