Test Coverage Strategy Framework

A practical guide to balancing test types, maximizing ROI, and building sustainable test suites.

Table of Contents

  1. The Test Pyramid
  2. Coverage Strategy by Project Type
  3. ROI Analysis
  4. Balancing Speed vs. Coverage
  5. Coverage Metrics That Matter
  6. Incremental Coverage Strategy
  7. Adapting Strategy Over Time

The Test Pyramid

Classic Test Pyramid

         ╱╲
        ╱  ╲
       ╱ UI ╲         ← 10% (E2E tests)
      ╱──────╲          • Slowest
     ╱        ╲         • Most brittle
    ╱ Service ╲       ← 20% (Integration tests)
   ╱            ╲       • Moderate speed
  ╱──────────────╲      • Focused scope
 ╱                ╲
│      Unit        │  ← 70% (Unit tests)
│                  │    • Fastest
│                  │    • Most stable
└──────────────┘    • Highest ROI

Why This Shape?

Unit Tests (70% - Foundation)