Test Coverage (scoverage)

Overview

  • Uses sbt-scoverage to measure line and branch coverage for Scala 2.13 and Scala 3 builds.
  • Global defaults: minimum 80% coverage, build fails if below.

How To Run Locally

  • Quick aliases:
    • From sbt shell: cov (aggregate + single root HTML) or covReport (current module HTML).
    • From terminal: sbt cov or sbt covReport.

  • Per-module coverage report: 1) sbt clean coverage test coverageReport 2) Open target/scala-*/scoverage-report/index.html for the current module.

  • Aggregate coverage across aggregated modules (root project): 1) sbt clean coverage test coverageAggregate coverageReport 2) The alias config avoids per-module HTML; open root target/scala-*/scoverage-report/index.html for the combined report.

CI Usage

  • Typical sequence: clean; coverage; test; coverageAggregate.
  • XML output (for CI tooling) is written to target/scala-*/scoverage-report/scoverage.xml.

Configuration

  • Defined in build.sbt:
    • coverageMinimumStmtTotal := 80 — required minimum statement coverage; adjust to taste.
    • coverageFailOnMinimum := false — fail build if under the minimum.
    • coverageHighlighting := true — better highlighting for coverage in reports.
    • coverageExcludedPackages — excludes runner and samples packages by default.

On‑the‑fly Overrides

  • For a one-off run: sbt "set coverageMinimumStmtTotal := 85" clean coverage test coverageReport
  • To disable fail on minimum for local runs: sbt "set coverageFailOnMinimum := false" coverage test

Expectations

  • Target at least 80% coverage for core library code.
  • Generated/entrypoint code (e.g., runner, samples) is excluded to keep focus on library logic.

Per‑module vs aggregate

  • By default, the setup generates a single HTML report at the root when using cov.
  • If you want individual project HTML reports, run coverageReport after switching to each project with project <name>.

Troubleshooting

  • If coverage is 0% across the board, ensure you ran coverage before test.
  • For multi-module runs, use coverageAggregate at the root project.