The ocov tool, short for OPA Coverage Report, colors into green and red the covered / not covered lines of the Rego policies, as output by opa test --coverage.
git clone --recursive https://github.com/c5t/ocov.git
cd ocov
NDEBUG=1 make .current/ocov
Copy .current/ocov somewhere into your $PATH. The following command does the job on both Mac and Linux.
sudo cp .current/ocov /usr/local/bin/
Either:
opa test ${TEST_ARGS} --coverage | ocov
Or:
opa test ${TEST_ARGS} --coverage > coverage.json
ocov --input coverage.json
There are also:
ocov --version # Or ocov -v
And:
ocov --help