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Ferrocat Docs

Test Coverage

ferrocat now exposes workspace-local Cargo aliases for coverage reporting through cargo-llvm-cov.

The long-term goal for the shipped library surface is:

  • 95%+ line coverage for ferrocat-po
  • 95%+ line coverage for ferrocat-icu
  • 95%+ line coverage for ferrocat once the umbrella crate contains measurable executable logic beyond re-exports

The coverage commands intentionally exclude:

  • ferrocat-bench, which is a benchmark harness rather than shipped library code
  • ferrocat-conformance, which is fixture data and expectations for the upstream snapshot

That keeps the report focused on the public and internal library crates that matter most in day-to-day changes:

  • ferrocat
  • ferrocat-po
  • ferrocat-icu

Baseline

Measured locally on 2026-03-18 with cargo coverage-summary plus a JSON summary export:

  • ferrocat-po: 88.10% line coverage
  • ferrocat-icu: 93.98% line coverage
  • ferrocat: N/A in llvm-cov today because the umbrella crate is almost entirely re-exports and does not currently surface measurable executable lines in the report

That means the current rollout is intentionally staged:

  • Phase 1: standardized local commands and CI artifact publication
  • Phase 2: crate-level guardrails close to the measured baseline
    • ferrocat-po >= 88%
    • ferrocat-icu >= 93%
    • ferrocat is still reported, but not percentage-gated until llvm-cov has measurable lines for the crate
  • Phase 3: raise the measurable core crates to 95%+

The next high-yield test targets after the current baseline are still:

  • ferrocat-po/src/api/catalog.rs
  • ferrocat-po/src/api/compile.rs
  • ferrocat-po/src/api/plural.rs
  • ferrocat-po/src/merge.rs
  • ferrocat-po/src/borrowed.rs
  • ferrocat-icu/src/parser.rs

Local Setup

Install the required tooling once:

rustup component add llvm-tools-preview
cargo install cargo-llvm-cov

Local Commands

Print a terminal summary:

cargo coverage-summary

Build an HTML report:

cargo coverage

The HTML output is written to:

target/coverage/html/index.html

Generate an LCOV file for external tooling:

cargo coverage-lcov

The LCOV output is written to:

target/lcov.info

CI

The GitHub Actions CI workflow runs a dedicated coverage job on Ubuntu, installs the required LLVM tooling, uploads the generated LCOV report to Codecov, and stores the same lcov.info file as a workflow artifact.

That same job now also exports target/coverage-summary.json and runs a small crate-aware gate script so the staged thresholds are enforced per crate instead of through one global blended percentage.

For private repositories, add a GitHub Actions repository secret named CODECOV_TOKEN.

For public repositories, tokenless upload may also work with codecov/codecov-action@v5 if token authentication has been disabled in the Codecov organization settings. If you want the least surprising setup, keep the CODECOV_TOKEN secret configured either way.