Coverage HTML Output

studio-design/openapi-contract-testing can emit a single self-contained HTML report via the html_output PHPUnit Extension parameter or the --html-output flag on openapi-coverage-merge. The file is intended for human review (PR comments, CI artifact preview, offline inspection).

A sample document is committed in the repository at docs/samples/coverage.html.

Design choices

• Single file. Inline CSS, no JavaScript, no external assets. Drops cleanly as a CI artifact and renders offline in any modern browser.
• <details>/<summary> for per-endpoint detail. Reviewers can expand only the endpoints they care about without depending on JavaScript.
• In-page anchor links. The top-level endpoint list links to per-endpoint detail sections so reviewers can jump directly to interesting rows.
• Safe escaping. All spec-derived strings (paths, operation IDs, skip reasons, content types) pass through htmlspecialchars($value, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8') so hostile spec content cannot inject markup.
• State markers. Each endpoint or response row carries a state-<value> CSS class so styling can be customised without changing the renderer. Endpoint-level classes mirror EndpointCoverageState: state-all-covered, state-partial, state-uncovered, state-request-only. Response-row classes mirror ResponseCoverageState: state-validated, state-skipped, state-uncovered. Only state-uncovered is shared between the two enums.

Generating the file

PHPUnit Extension:

<extensions>
  <bootstrap class="Studio\OpenApiContractTesting\PHPUnit\OpenApiCoverageExtension">
    <parameter name="spec_base_path" value="openapi" />
    <parameter name="html_output" value="build/coverage.html" />
  </bootstrap>
</extensions>

Paratest merge CLI:

vendor/bin/openapi-coverage-merge \
  --spec-base-path=openapi \
  --html-output=build/coverage.html

Multiple formats

output_file, junit_output, json_output, and html_output are independent; setting any combination writes all configured formats. A write failure on one format does not block the others. Severity follows the existing convention: subscriber WARN-and-continue, CLI FATAL + exit 1.

Note on GITHUB_STEP_SUMMARY. The HTML output is not appended to GITHUB_STEP_SUMMARY (which is Markdown-only by design; GitHub renders the file as Markdown, so an HTML payload would be escaped). Use html_output for artifact uploads and output_file / github_step_summary for the Markdown summary.

Future extensions

The current shape is intentionally minimal. If a multi-page report (per-spec files, asset directory) is requested, a separate html_output_dir parameter will be added — html_output will continue to mean "single self-contained file" so existing pipelines do not need to migrate.