JaCoCo with multi-module Maven project - Only record coverage by module owned tests

Question

We have a large Maven project with about 50 modules. Today we have a good setup where we get a combined JaCoCo coverage for the whole project. We also use the final binary generated by JaCoCo for custom coverage logic.

We would like to implement a more strict coverage policy where only tests in the same module contribute to the overall coverage. We want every module to be responsible for its own tests and coverage.

For example. Module A depends on module B. A has code that makes use of code in B. When tests in A is run, we do not want to have coverage from any class in B recorded.

Is this setup possible? Trying around, I find that JaCoCo has many options for filtering when generating the final report, but I'd like to do this in the first step, when the coverage is collected.

Eventually, I'd like to end up with a JaCoCo exec file in each module's target directory that only has classes recorded from its own module. It would be perfectly fine if we had to do some configuration on a module-by-module basis like having an explicit package expression for inclusion.

Answer 1

Trying around, I find that JaCoCo has many options for filtering when generating the final report, but I'd like to do this in the first step, when the coverage is collected.

There is also options for filtering during collection - see includes and excludes options of JaCoCo Java Agent and corresponding options of prepare-agent in jacoco-maven-plugin .

Build of JaCoCo itself uses them exactly for this.