Coverage

Upload Flutter test coverage to Codecov and show a badge in README

When I build a Flutter project, I like to set up coverage early. It helps me track test quality on every push and pull request.

How to create a test badge like this?

Codecov badge

This badge is very useful because we can quickly see the test coverage status in the repository.

Step 1: Login to Codecov

Go to: https://codecov.io Login with your GitHub account.

Step 2: Generate lcov.info in local

Run:

flutter test --coverage

After that, you will have:

coverage/lcov.info

Step 3: Create GitHub Actions workflow

Create file:

.github/workflows/coverage.yml

Add this content:

name: Coverage

on:
  push:
    branches: [ main ]
  pull_request:

jobs:
  test-and-upload:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: subosito/flutter-action@v2
        with:
          channel: stable

      - run: flutter pub get
      - run: flutter test --coverage

      - uses: codecov/codecov-action@v4
        with:
          files: coverage/lcov.info

Important: Public vs Private Repository

This workflow usually works directly for public repositories.

For private repositories, add CODECOV_TOKEN in GitHub Secrets, then update the Codecov step:

      - uses: codecov/codecov-action@v4
        with:
          files: coverage/lcov.info
          token: ${{ secrets.CODECOV_TOKEN }}

Step 4: Commit and push

Run:

git add .github/workflows/coverage.yml
git commit -m "Add coverage workflow"
git push

Step 5: Check CI/CD status

Go to your GitHub repository -> Actions tab. Workflow Coverage should be green.

Step 6: View result on Codecov

Open:

https://app.codecov.io/gh/ngmduc2012/my_lang

Step 7: Add coverage badge to README

Add this code:

[![codecov](https://codecov.io/gh/ngmduc2012/my_lang/branch/main/graph/badge.svg)](https://codecov.io/gh/ngmduc2012/my_lang)

Note

If upload fails, check repository visibility and token setup first.

Conclusion

This is my simple way to set up Flutter coverage with Codecov. It is easy to maintain and very helpful when reviewing pull requests.

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