PRs that don't change tests showing a change in coverage

[carusooo]

Describe a bug

PRs that don't change tests at all are showing a change in coverage.

1. I make a change to a README.md file
2. Upload the PR
3. The coverage shows changes between 2-15%

Expected behavior

No changes to coverage should be displayed.

Details

• Action version: v2

• OS: linux

• action.yml file

  name: Pull Request - Backend
  on:
    pull_request:
      paths:
        - "backend/**"
  
  defaults:
    run:
      working-directory: backend
  
  jobs:
    lint-and-test:
      runs-on: ubuntu-20.04
      env:
        MODE: CI
  
      steps:
        - name: checkout
          uses: actions/checkout@v2
  
        - name: install node.js
          uses: actions/setup-node@v1
          with:
            node-version: 16.x
  
        - name: install node packages
          run: npm install
  
        - name: run lint
          run: npm run lint
  
        - uses: ArtiomTr/jest-coverage-report-action@v2
          id: coverage
          with:
            working-directory: backend
            github-token: ${{ github.token }}
            output: report-markdown
            annotations: none
        - uses: marocchino/sticky-pull-request-comment@v2
          with:
            message: ${{ steps.coverage.outputs.report }}
  
        - name: ensure clean working directory
          run: |
            rm report.json
            if files=$(git ls-files --exclude-standard --others --modified) && [[ -z "$files" ]]; then
              exit 0
            else
              echo ""
              echo "Working directory has been modified:"
              echo ""
              git status --short
              echo ""
              exit 1
            fi
    build:
      runs-on: ubuntu-20.04
      steps:
        - name: checkout
          uses: actions/checkout@v2
  
        - name: install node.js
          uses: actions/setup-node@v1
          with:
            node-version: 16.x
  
        - name: install node packages
          run: npm install
  
        - name: run build
          run: npm run build        

• Screenshots

  Coverage report for backend

  St.❔	Category	Percentage	Covered / Total
  🔴	Statements	45.89% (+8.99% 🔼)	1241/2704
  🔴	Branches	32% (+14.1% 🔼)	136/425
  🔴	Functions	36.25% (+4.42% 🔼)	141/389
  🔴	Lines	44.99% (+2.05% 🔼)	1154/2565

  Test suite run success

  88 tests passing in 27 suites.

  Report generated by 🧪jest coverage report action from 68938ffdb6cf7e29a6cef298820e83482370bb2a

Additional context

The above output is generated based on a change to a README.md file (not used in tests). The repository uses squash-merge commits.

[ArtiomTr]

Hello @carusooo 👋,

I am unable to reproduce this issue. Could you please provide a minimal reproduction repository? This would significantly help with the debugging process.