Integration Testing

What is Integration Testing?

Integration testing verifies that individual modules or units work correctly together when combined, focusing on the interfaces and data flow between them.

Common Approaches

• Big Bang Integration: All modules are combined at once and tested together.
• Top-Down Integration: Testing starts from top-level modules, using stubs for lower-level modules not yet developed.
• Bottom-Up Integration: Testing starts from lower-level modules, using drivers to simulate higher-level modules.
• Sandwich/Hybrid Integration: Combines both top-down and bottom-up approaches.

Why It Matters

Even if individual units pass their own tests, problems in how they communicate — mismatched data formats, incorrect API calls, timing issues — can only be caught once modules are integrated.