Scoverage

This module allows you to generate code coverage reports for Scala projects with Scoverage via the scalac-scoverage-plugin.

To declare a module for which you want to generate coverage reports you can extends the mill.contrib.scoverage.ScoverageModule trait when defining your module. Additionally, you must define a submodule that extends the ScoverageTests trait that belongs to your instance of ScoverageModule.

build.mill

package build
import $ivy.`com.lihaoyi::mill-contrib-scoverage:`
import mill.contrib.scoverage.ScoverageModule

object foo extends ScoverageModule  {
  def scalaVersion = "2.13.15"
  def scoverageVersion = "2.1.1"

  object test extends ScoverageTests with TestModule.ScalaTest {
    def ivyDeps = Agg(ivy"org.scalatest::scalatest:3.2.19")
  }
}

In addition to the normal tasks available to your Scala module, Scoverage modules introduce a few new tasks and changes the behavior of an existing one.

mill foo.scoverage.compile              # compiles your module with test instrumentation
                                        # (you don't have to run this manually, running the test task will force its invocation)

mill foo.test                           # tests your project and collects metrics on code coverage
mill foo.scoverage.htmlReport           # uses the metrics collected by a previous test run to generate a coverage report in html format
mill foo.scoverage.xmlReport            # uses the metrics collected by a previous test run to generate a coverage report in xml format
mill foo.scoverage.xmlCoberturaReport   # uses the metrics collected by a previous test run to generate a coverage report in Cobertura's xml format

The measurement data is by default available at out/foo/scoverage/data/dest, the html report is saved in out/foo/scoverage/htmlReport.dest/, and the xml report is saved in out/foo/scoverage/xmlReport.dest/.

Multi-module projects

If you’re using Scoverage on a project with multiple modules then an additional module, ScoverageReport, is available to help aggregate the reports from all ScoverageModules.

Simply define a scoverage module at the root of your project as shown:

  object scoverage extends ScoverageReport {
    override def scalaVersion     = "<scala-version>"
    override def scoverageVersion = "<scoverage-version>"
  }

This provides you with various reporting functions:

mill __.test                                 # run tests for all modules
mill scoverage.htmlReportAll                 # generates report in html format for all modules
mill scoverage.xmlReportAll                  # generates report in xml format for all modules
mill scoverage.xmlCoberturaReportAll         # generates report in Cobertura's xml format for all modules
mill scoverage.consoleReportAll              # reports to the console for all modules

The aggregated report will be available at either out/scoverage/htmlReportAll.dest/ for html reports or out/scoverage/xmlReportAll.dest/ for xml reports.