Testing Strategies & Methodologies

Comprehensive testing strategies for building reliable, high-quality software systems.

Test Pyramid

        UI/E2E Tests
       /            \
      /              \
   Integration Tests
    /                \
  /                  \
Unit Tests

• •Unit Tests: Fast, isolated, low-level (60%)
• •Integration Tests: Component interactions (30%)
• •E2E Tests: Full system workflows (10%)

Testing Types

Unit Testing

• •Test individual functions/methods
• •Mocking dependencies
• •Fast execution
• •Examples: Jest, Pytest, Mocha

Integration Testing

• •Test component interactions
• •With real databases/services
• •Slower than unit tests
• •Examples: Postman, Supertest

End-to-End Testing

• •Complete user workflows
• •Browser automation
• •Slowest but most realistic
• •Examples: Cypress, Selenium, Playwright

Property-Based Testing

• •Generate random inputs
• •Verify invariants hold
• •Find edge cases
• •Examples: Hypothesis, QuickCheck

Contract Testing

• •Verify API contracts between services
• •Consumer and provider sides
• •Microservices testing
• •Examples: Pact, Spring Cloud Contract

Chaos Engineering

• •Inject failures intentionally
• •Test system resilience
• •Find weak points
• •Tools: Chaos Toolkit, Gremlin

Best Practices

1. •Test Behavior, Not Implementation - Focus on what, not how
2. •Keep Tests Fast - Run frequently
3. •Isolate Dependencies - Mock external systems
4. •Clear Test Names - Describe what's being tested
5. •DRY Tests - Eliminate duplication
6. •Test Edge Cases - Boundaries, nulls, errors
7. •Use Test Fixtures - Consistent setup
8. •Automate Testing - CI/CD integration

Test Naming Convention

test_[function]_[scenario]_[expected_outcome]

Example:
test_calculateDiscount_withValidCode_returnsDiscountedPrice
test_loginUser_withInvalidPassword_throwsAuthenticationError

Example Test Patterns

AAA Pattern (Arrange-Act-Assert)

test('calculateTotal with items', () => {
  // Arrange
  const cart = new Cart();
  cart.addItem({ price: 10 }, 2);
  
  // Act
  const total = cart.getTotal();
  
  // Assert
  expect(total).toBe(20);
});

BDD (Behavior-Driven Development)

Feature: User Authentication
  Scenario: Login with valid credentials
    Given a user with email "test@example.com"
    When the user logs in with correct password
    Then they should see the dashboard

Metrics

• •Code Coverage: % of code executed by tests (aim for 80%+)
• •Test Pass Rate: % of tests passing
• •Test Execution Time: How long tests take to run
• •Mutation Score: % of introduced bugs caught

Common Pitfalls to Avoid

• •Over-testing trivial code
• •Not testing error paths
• •Flaky tests (non-deterministic)
• •Testing implementation details
• •Ignoring performance in tests
• •Not testing concurrency

References

• •Test Driven Development (Kent Beck)
• •Growing Object-Oriented Software, Guided by Tests
• •Working Effectively with Legacy Code (Michael Feathers)
• •Testing Strategies for Microservices
• •Chaos Engineering (whitepaper)