Checking Code Coverage
Use the Bisect tool to discover how much of your code is being tested
Overview
Code coverage can be a good indicator into how well your code does what it is supposed to do. Of course, the goal is not to blindly chase 100% coverage, but to use the output to help you write correct and maintainable code.
Recommended Workflow
Setting up code coverage requires changes to your dune file for the libraries you want to cover. You will also need to update your opam file to depend on ppx_bisect. The opam file will add bisec_ppx as a dependency:
depends: [
...
"bisect_ppx" {dev & >= "2.0.0"}
]
And in the a library we want to cover, say a library called numberz we need to add a preprocessor.
(library
(name numberz)
(public_name numberz)
(preprocess (pps bisect_ppx --conditional)))
To run the tests with bisect enabled and to get the summary of the coverage you can run:
# This will produce the bisect results
BISECT_ENABLE=yes dune runtest --force
# Tells you in the terminal
bisect-ppx-report summary
# Produces coverage in _coverage directory
bisect-ppx-report html