🧪 Testing, Quality & Continuous Delivery in Modern Development

Software quality is not achieved at the end — it’s built in every step of development. From unit testing to CI/CD pipelines, clean automation ensures reliability, scalability, and developer confidence. 🚀

Master testing, automation, and delivery pipelines to ensure quality at every stage of development.

1. Testing Mindset 🧠

Testing is not just about catching bugs — it’s about designing better software. Good tests validate behaviour, drive design decisions, and improve maintainability.

  • Unit Tests: Test individual methods or components in isolation.
  • Integration Tests: Verify interactions between components or services.
  • End-to-End (UI) Tests: Simulate user journeys through the entire system.

Use the Test Pyramid (Mike Cohn):

  • 🔹 Unit tests → fast, numerous
  • 🔹 Service/integration tests → fewer
  • 🔹 UI/end-to-end tests → minimal but critical

2. Test-Driven Development (TDD) 🔴🟢⚪

TDD encourages writing tests before code. Follow the Red → Green → Refactor cycle:

  1. 🔴 Red: Write a failing test that defines expected behaviour.
  2. 🟢 Green: Write minimal code to make the test pass.
  3. ⚪ Refactor: Improve the code while keeping tests green.

// Example: TDD for Calculator
@Test
void shouldAddTwoNumbers() {
    Calculator calc = new Calculator();
    assertEquals(4, calc.add(2, 2));
}

3. Behaviour-Driven Development (BDD) 💬

BDD extends TDD with human-readable tests in natural language.

Common frameworks: Cucumber, JBehave.


Scenario: Successful login
  Given a user on the login page
  When they enter valid credentials
  Then they should be redirected to the dashboard

Annotations in Cucumber:

  • @Given — initial context
  • @When — user action
  • @Then — expected outcome
  • @And — continues any previous step

4. Mocks, Stubs & Test Doubles 🧩

  • Stub: Returns predefined responses (no logic).
  • Mock: Verifies that specific methods were called (behaviour verification).
  • Spy (Partial Mock): Wraps a real object but overrides some methods for focused testing.
  • Fake: Lightweight implementation (e.g., in-memory DB).

// Mockito example
UserRepository repo = mock(UserRepository.class);
when(repo.findUser("admin")).thenReturn(new User("admin"));
verify(repo).findUser("admin");

5. WireMock for Integration Testing ⚡

Once unit and behavioural tests are solid, test integrations safely. WireMock simulates external APIs with a local HTTP server returning predefined responses.


// Example WireMock stub
stubFor(get(urlEqualTo("/api/user/123"))
  .willReturn(aResponse()
    .withStatus(200)
    .withBody("{ \"name\": \"John\" }")));

6. Continuous Integration & Continuous Delivery (CI/CD) 🚀

CI/CD in this article is conceptual: CI/CD pipelines support software quality by ensuring automated building, testing, and readiness for deployment.

  • CI: Automatically build and test code on each change to catch regressions early.
  • CD: Keep the application deployable at any time — either manually or automatically.

For detailed pipeline examples, deployment automation, and strategies, see the dedicated DevOps article in this series.

7. Quality Gates & Static Analysis 🔍

Prevent bad code from entering production with automated quality tools:

  • SonarQube — code smells, coverage, duplication
  • Checkstyle, PMD — enforce code style & rules
  • Polaris / WhiteSource — dependency & security checks

Integrate these directly in your CI/CD pipeline to enforce Definition of Done (DoD).

8. Definition of Ready (DoR) & Definition of Done (DoD) 🏁

  • DoR: Story has clear requirements, acceptance criteria, estimation, and business value.
  • DoD: Story is complete when developed, tested, reviewed, documented, and deployed.

🌟 Conclusion

Testing and automation are the backbone of software excellence. By embracing TDD, BDD, CI/CD, and quality gates, your system becomes reliable, scalable, and production-ready — every day. ✅

Labels: Testing, Java, TDD, BDD, CI/CD, Quality, Automation

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