fix(action): add optional support for removed files in changed coverage

[jeduardoc]

Summary

This PR adds an opt-in way to ignore removed files from changed coverage calculations without changing the current default behavior.

The goal is to address a real integration issue caused by removed files returned by the GitHub compare API while preserving backward compatibility for repositories already relying on the current output semantics.

Background

While investigating a failing downstream workflow that consumes madrapps/jacoco-report@v1.7.2, we found a scenario where the compare API included files with status: removed in the changed file list.

Those files do not exist in the JaCoCo XML report, but they still flow through the changed-files processing path. This can distort the changed coverage result used by downstream workflows.

At the same time, changing the existing default behavior globally would be risky because repositories may already depend on the current output contract.

Root Cause

The action builds its changed-file list directly from the GitHub compare API response and, today, does not provide a way to exclude removed files.

When removed files appear in the diff:

• they may participate in the changed-file matching flow even though they cannot exist in the report XML
• downstream consumers cannot opt into safer behavior without patching their own workflows

What changed

Functional change

A new optional input was added:

• ignore-removed-files (default: false)

When enabled, the action excludes compare API entries where status === 'removed' before building the internal changed-file list.

Compatibility

This implementation intentionally keeps the current default behavior unchanged:

• existing users do not need to change anything
• current tests and existing output expectations remain valid by default
• repositories affected by removed files can opt in explicitly

Tests

• preserved the previous assertions for the default behavior
• added regression coverage proving that removed files are still included when the option is disabled
• added regression coverage proving that removed files are excluded when the option is enabled

Documentation

• documented the new ignore-removed-files input in README.md
• documented the new input in action.yml
• kept the existing coverage-changed-files output description unchanged

Why this approach

This is the narrowest fix with the lowest compatibility risk:

• it solves the removed-files scenario for affected repositories
• it avoids silently changing the output contract for everyone else
• it gives maintainers a clear migration path through an explicit opt-in input

Validation

Executed locally:

• npm test -- --runInBand __tests__/action_single.test.ts __tests__/action_multiple.test.ts __tests__/action_aggregate.test.ts __tests__/action_empty_aggregate.test.ts __tests__/action_empty_multiple.test.ts __tests__/action_empty_report.test.ts
• npm run build

Commits

• c977eee fix(action): add optional support for removed files in changed coverage
• 87f1215 docs(readme): document the ignore-removed-files input

References

Related issues in this repository:

• #71 Incorrect value for steps.jacoco.outputs.coverage-changed-files
  • Incorrect value for steps.jacoco.outputs.coverage-changed-files #71
• #42 Jacoco Ignored files are shown as 0% coverage
  • Jacoco Ignored files are shown as 0% coverage #42
• #170 Discrepancy with the Coverage report
  • Discrepancy with the Coverage report  #170

Additional context:

• GitHub compare API file status documentation
  • https://docs.github.com/en/rest/commits/commits#compare-two-commits
• Current action version reference in the README
  • madrapps/jacoco-report@v1.7.2

This PR focuses specifically on making removed-file handling available as an explicit compatibility-safe option.