Verification

Equivalence testing

Every commit is compared against Java FastQC reference output across 18 test cases covering all CLI flag combinations. The report shows text diffs with word highlighting, pixel-level image comparison, and side-by-side SVG previews.

View the latest equivalence report

What is tested

fastqc_data.txt and summary.txt must be byte-identical after applying known-difference patches
fastqc_report.html must be structurally identical after normalizing embedded images
SVG charts must be structurally identical after normalizing font and rendering differences
PNG charts are compared pixel-by-pixel with a configurable tolerance (currently 12%)

What is different

Text output is identical. Some non-text outputs differ because the rendering stack is different:

PNG charts are rendered via resvg + tiny-skia instead of Java2D. Antialiasing differs, producing 1-2% pixel differences.
SVG charts use a bundled font (Liberation Sans) instead of system Arial, so text positions shift by a few pixels.
The HTML report is structurally identical once you strip out the embedded chart images (which differ for the same rendering reasons).

None of this affects analysis results. fastqc_data.txt and summary.txt are byte-identical.

CI integration

The comparison runs on every commit and pull request via GitHub Actions. If any strict file differs from reference after patching, the build fails. The HTML report is uploaded as a build artifact on every run (pass or fail) so reviewers can inspect differences visually.

Running locally

cargo build --release
uv run tests/equivalence/compare.py --binary ./target/release/fastqc

Writes the report to tests/equivalence/reports/equivalence_report.html.