6 - Test what you change with Carryforward Flags

Although Flags can help separate out different test suites, not every project will run the entire test suite for every commit. Carryforward Flags can be used here to maintain consistent coverage values.

Update CI workflows to run on applicable changes

Pull the latest from main and create a new branch step6

git checkout main
git pull
git checkout -b 'step6'

Let’s set up our demo repository to only run workflows if the affected code is changed.

GitHub Actions

Edit the on: section of both workflows

...
on:
  push:
    paths:
      - 'api/**'

...
on:
  push:
    paths:
      - 'web/**'

CircleCI

Running jobs based on files changed in a directory requires CircleCI's path-filtering orb and dynamic config.

Due to this issue, be sure to replace <<pipeline.parameters.test-api-job>> and <<pipeline.parameters.test-frontend-job>> with <<pipeline.parameters.test-api-job>> and <<pipeline.parameters.test-frontend-job>> , respectively.

You will need to enable dynamic config.

version: 2.1

setup: true

orbs:
  path-filtering: circleci/[email protected]

workflows:
  jobs:
    - path-filtering/filter:
        mapping: |
          api/.* test-api-job true
          web/.* test-frontend-job true

version: 2.1

orbs:
  codecov: codecov/[email protected]

parameters:
  test-api-job:
    type: boolean
    default: false
  test-frontend-job:
    type: boolean
    default: false

jobs:
  test-api:
    docker:
      - image: cimg/python:3.10.2
          name: Install requirements
          command: pip install -r api/requirements.txt
      - run:
          name: Run tests and collect coverage
          command: pytest --cov --cov-report xml .
      - codecov/upload:
          flags: backend
  test-frontend:
    docker:
      - image: cimg/node:17.6.0
    steps:
      - checkout
      - run:
          name: Install requirements
          command: cd web && npm install
      - run:
          name: Run tests and collect coverage
          command: cd web && npm run test
      - codecov/upload:
          flags: frontend

workflows:
  test-api-workflow:
    when: << pipeline.parameters.test-api-job >>
    jobs:
      - test-api
  test-frontend-workflow:
    when: << pipeline.parameters.test-frontend-job >>
    jobs:
      - test-frontend

Now, if we make a change to only code in the web directory, the frontend workflow will run.

Add coverage to the frontend

Let’s add a test to our calculator.

...
  test('test operation', () => {
    const calculator = new calc.Calculator();
    calculator.chooseOperation('+');
    expect(calculator.operation).toBeUndefined();

    calculator.appendNumber(1);
    calculator.appendNumber(2);
    calculator.chooseOperation('+');
    expect(calculator.currentOperand).toBe('');
    expect(calculator.operation).toBe('+');
    expect(calculator.previousOperand).toBe('12');

    calculator.appendNumber(3);
    calculator.appendNumber(4);
    expect(calculator.currentOperand).toBe('34');
    expect(calculator.operation).toBe('+');
    expect(calculator.previousOperand).toBe('12');
  })
...

Run cd web && npm run test to ensure that the test has been added in correctly.

Turn Flags into Carryforward Flags

Finally, we will need to make a change to our codecov.yml file to ensure that Flags are marked as Carryforward.

...
flag_management:
  default_rules:
    carryforward: true
...

Commit and push your changes to GitHub.

git add .
git commit -m 'step6: add Carryforward Flags'
git push origin step6

Notice that only the frontend workflow runs. In the Flag section of the Codecov comment, you will only see the frontend Flag.

Conclusion

At this point, you have worked through the major features of Codecov. From here, you can explore other advanced aspects of the product.