Regression Testing

Test Selection Strategies

Change-Based Test Selection

// Analyze changed files and select impacted tests
function selectTests(changedFiles: string[]): string[] {
  const testsToRun = new Set<string>();

  for (const file of changedFiles) {
    // Direct tests
    testsToRun.add(`${file.replace('.ts', '.test.ts')}`);

    // Dependent tests (via coverage mapping)
    const dependentTests = testCoverage[file] || [];
    dependentTests.forEach(t => testsToRun.add(t));
  }

  return Array.from(testsToRun);
}

// Example: payment.ts changed
// Runs: payment.test.ts, checkout.integration.test.ts, e2e/purchase.test.ts

Regression Suite Pyramid

         /\
        /  \  Full Regression (weekly)
       /    \  - All tests (2-4 hours)
      /------\
     /        \  Extended Regression (nightly)
    /          \  - Unit + integration + critical E2E (30-60 min)
   /------------\
  /              \  Quick Regression (per commit)
 /________________\  - Changed code + smoke tests (5-10 min)

CI/CD Integration

# .github/workflows/regression.yml