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Generating coverage reports

The reporting Action does not run your tests or install coverage tools. Your CI step produces a report file (LCOV, Cobertura XML, JaCoCo XML, or Go's native coverage profile); the Action reads it. This page shows the command for each supported language. Coverage Tracker not deployed yet? Start with the Installation Guide.

Format is detected automatically from file content — you don't set it explicitly:

  • First line mode: set|count|atomic → Go coverage profile
  • Starts with TN: / SF: → LCOV
  • XML root <coverage> → Cobertura
  • XML root <report> → JaCoCo

coverage-tool is only required when the format resolves to Cobertura — it's the generator name, used to correct for known differences between Cobertura writers (see the Cobertura quirks table below).

Coverage

Language Tool Format Command Default path
Go go tool cover native profile go test -coverprofile=coverage.out ./... coverage.out
Python coverage.py LCOV coverage run -m pytest && coverage lcov -o coverage.lcov coverage.lcov
JS/TS Istanbul (nyc / vitest / jest) LCOV vitest run --coverage --coverage.reporter=lcov coverage/lcov.info
Rust cargo-llvm-cov LCOV cargo llvm-cov --lcov --output-path lcov.info lcov.info
C/C++ gcovr LCOV gcovr --lcov -o coverage.lcov coverage.lcov
C# coverlet LCOV dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=lcov coverage.info
Java JaCoCo JaCoCo XML mvn test jacoco:report (Maven) or ./gradlew jacocoTestReport (Gradle) target/site/jacoco/jacoco.xml / build/reports/jacoco/test/jacocoTestReport.xml
Bash kcov Cobertura kcov --include-path=. coverage/ ./script.sh dynamic — set coverage-path
Clojure Cloverage LCOV lein cloverage --lcov target/coverage/lcov.info
Dart Flutter test / coverage pkg LCOV flutter test --coverage coverage/lcov.info
Elixir ExCoveralls LCOV mix coveralls.lcov cover/lcov.info
Erlang covertool Cobertura rebar3 do eunit, cover, covertool generate dynamic — set coverage-path
Haskell hpc + hpc-codecov LCOV cabal test --enable-coverage && hpc-codecov cabal:all -f lcov -o lcov.info lcov.info
Lua LuaCov + luacov-reporter-lcov LCOV luacov -r lcov luacov.report.out
Perl Devel::Cover + lcov's perl2lcov LCOV cover -test && perl2lcov -o coverage.lcov coverage.lcov
PHP PHPUnit Cobertura XDEBUG_MODE=coverage vendor/bin/phpunit --coverage-cobertura=coverage.xml coverage.xml
Ruby SimpleCov + simplecov-lcov LCOV (configure SimpleCov::Formatter::LcovFormatter in spec_helper.rb) then rspec coverage/lcov.info

Note

Go is parsed directly Go is read from its native coverage profile — no LCOV/Cobertura conversion, so no accuracy loss.

Warning

JaCoCo isn't Cobertura Java's JaCoCo XML is a different schema, not a dialect of Cobertura XML. It's parsed with its own module in the reporter, not the Cobertura path.

Automatic report discovery

The "Default path" columns on this page are real probe targets, not just conventions. When coverage-path is unset, the Action probes these paths in a fixed order and uses the first hit:

  1. coverage.out
  2. coverage/lcov.info
  3. lcov.info
  4. coverage.lcov
  5. coverage.info
  6. cover/lcov.info
  7. target/coverage/lcov.info
  8. target/site/jacoco/jacoco.xml
  9. build/reports/jacoco/test/jacocoTestReport.xml
  10. coverage.xml
  11. luacov.report.out

If nothing is found, the Action fails with an error that lists every path it probed. An explicit coverage-path input always wins over probing.

Note

kcov and covertool need an explicit path Their default output paths contain dynamic segments (the script name, the app name) — write the file wherever the tool puts it and point coverage-path at it.

Complexity and duplication (optional)

Only coverage is required. Complexity and duplication are opt-in: set the path explicitly (complexity-path / duplication-path), or write the report to the default location below and the Action picks it up automatically.

Metric Tool Command Default path
Complexity — Go gocyclo gocyclo -avg ./... > gocyclo.txt gocyclo.txt
Complexity — Python Radon radon cc -j . > radon.json radon.json
Complexity — everything else Lizard lizard --xml > lizard-report.xml lizard-report.xml
Duplication — any language jscpd npx jscpd . --reporters json --output ./jscpd-report jscpd-report/jscpd-report.json

There is no complexity-tool input — Radon (JSON), gocyclo (plain text), and Lizard (XML) are recognized by content shape. When probing finds more than one complexity file, precedence is radon.json → gocyclo.txt → lizard-report.xml; an explicit complexity-path overrides probing entirely.

Warning

Thresholds make reports mandatory If max-complexity or max-duplication is configured and no report file for that metric is found — neither at the input path nor at a default location — the Action fails with an actionable error. A metric is skipped silently only when it is both unconfigured and absent.

Note

Java gets complexity for free JaCoCo's COMPLEXITY counter is already in the coverage report — no separate step needed for Java. An explicit complexity-path (or a probed complexity file) overrides the JaCoCo-derived value.

Cobertura quirks

Cobertura XML is a shared DTD, not an enforced spec — generators disagree on two things the reporter corrects for based on coverage-tool:

coverage-tool Trust branch-rate? Notes
gocover-cobertura No — always 0 Go's block-based coverage can't map to branches
kcov Yes
covertool Yes
phpunit Yes
gcovr Yes

If your coverage-tool isn't listed, the reporter treats branch-rate as trustworthy by default — open an issue if that's wrong for your generator.