Introduction

Testing how multiple modules/components interact (service + repository + DB/API).

• Ensure components integrate correctly.
• Catch errors missed in unit tests.

Test Business Flow correct or not

• How components work together
• Service → Repository → DB
• End-to-end behavior of a use case

Characteristics

• Scope: multiple real classes/modules.
  • Test wiring, see got wiring issue or not.
• Slower than unit tests → seconds.
• Environment-dependent → real DB, API, message queues.
  • Rollback / cleanup to avoid DB pollution.
• Closer to production behavior.

Flow

HTTP Request
↓
Controller (REAL)
↓
Service (REAL)
↓
Repo (REAL)
↓
DB (REAL)