Automated Testing

Learning objectives#

• Apply the test pyramid
• Run unit and integration tests in CI
• Add a few end-to-end tests
• Keep test suites fast and reliable

Explanation#

Test pyramid: many fast unit tests, fewer integration tests (real database or API), and a handful of end-to-end tests through the UI.

Integration tests can use real dependencies in containers (Testcontainers) instead of mocks.

End-to-end tools such as Playwright drive a real browser for critical journeys like login and checkout.

Flaky tests destroy trust — fix or quarantine them quickly.

Code example: Tests in parallel jobs#

1name: test
2on: [pull_request]
3jobs:
4  unit:
5    runs-on: ubuntu-latest
6    steps:
7      - uses: actions/checkout@v4
8      - uses: actions/setup-dotnet@v4
9        with: { dotnet-version: '9.0.x' }
10      - run: dotnet test tests/Shop.UnitTests --collect:"XPlat Code Coverage"
11

12  integration:
13    runs-on: ubuntu-latest
14    steps:
15      - uses: actions/checkout@v4
16      - uses: actions/setup-dotnet@v4
17        with: { dotnet-version: '9.0.x' }
18      - run: dotnet test tests/Shop.IntegrationTests     # uses Testcontainers for SQL Server
19

20  e2e:
21    needs: [unit, integration]
22    runs-on: ubuntu-latest
23    steps:
24      - uses: actions/checkout@v4
25      - run: npx playwright install --with-deps chromium
26      - run: npx playwright test tests/e2e/checkout.spec.ts

Unit and integration tests run in parallel; the slower end-to-end checkout test runs only if both pass.

This example is illustrative. Copy or download it and run it in your own environment; the expected output is shown above.

Step-by-step explanation#

1. Unit tests give fast feedback with coverage.
2. Integration tests run against a real SQL Server container.
3. needs: makes E2E wait for the cheaper tests.
4. Only critical journeys get E2E tests.

Real-world use case#

Common mistakes#

Best practices#

• Many unit, some integration, few E2E
• Real dependencies via containers
• Fix flaky tests immediately
• Run tests on every PR

Remember this#

Practice exercise#

1A unit test — it is pure logic and runs in milliseconds.

Mini quiz#

Want more? Practise all DevOps MCQs · DevOps interview questions

Related topics#

My notes#

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