Bisect_ppx is a code coverage tool for OCaml. It helps you test thoroughly by showing which parts of your code are not tested. You can also use it for tracing: run one test, and see what is visited.
Most of these commands go in a
Makefile or other script, so that you only have
to run that script, then refresh your browser.
opam install bisect_ppx
You can also install without OPAM.
ocamlfind c -package bisect_ppx -c my_code.ml ocamlfind c -c my_tests.ml ocamlfind c -linkpkg -package bisect_ppx my_code.cmo my_tests.cmo
Run your test binary. In addition to testing your code, it will produce one or more files with names like
./a.out # Produces bisect0001.out
Generate the coverage report.
bisect-ppx-report -I _build/ -html coverage/ bisect*.out`
In each file of the report,
- Green lines contain expressions, all of which were visited.
- Red lines contain expressions, none of which were visited.
- Yellow lines contain expressions, some of which were visited, but others not.
- White lines are those that don't contain visitable expressions. They may have type declarations, keywords, or something else that Bisect_ppx did not, or cannot instrument.
You can submit a coverage report to Coveralls.io using ocveralls. Note that Bisect_ppx reports are more precise than Coveralls, which only considers whole lines as visited or not.
See also the advanced usage.
Bisect_ppx in practice
A small sample of projects using Bisect_ppx:
Bisect_ppx is available under the Mozilla Public License 2.0 (MPL). To summarize, you can incorporate Bisect_ppx into proprietary projects. If you make modifications to Bisect_ppx, you have to open-source them. The rest of your project remains proprietary.
Essentially, this is like the BSD or MIT licenses, except that if you include a customized Bisect_ppx in a release (as opposed to private use), you have to make the altered source visible. This can be done by contributing the changes back, keeping Bisect_ppx in a visible fork, or if your bigger project itself also happens to be open source.
Besides proprietary licenses, MPL is compatible with BSD/MIT/Apache- and (L)GPL-licensed projects. See the MPL 2.0 FAQ.
The Ocamlbuild plugin is dedicated to the public domain.
Bug reports and pull requests are warmly welcome. Bisect_ppx is developed on GitHub, so please open an issue.
To get the latest development version of Bisect_ppx using OPAM, run
opam source --dev-repo --pin bisect_ppx
You will now have a
bisect_ppx subdirectory to work in.