What integration tests cover

Integration tests verify interactions between units.

Examples:

• repository ↔ database
• API client ↔ real HTTP server (or test server)
• service ↔ message queue

When integration tests are valuable

• you want confidence in boundary behavior
• you’re worried about schema changes
• you use third-party APIs/libraries

Diagram: integration boundary

  graph LR
A[Business logic] --> B[Repository]
B --> C[(Database)]

A --> D[HTTP client]
D --> E[External API]

Tips

• Keep them fewer than unit tests
• Use test databases/containers where possible
• Make setup/teardown reliable

🧪 Try It Yourself

Exercise 1 – Write a unittest TestCase

Exercise 2 – assertRaises

Exercise 3 – setUp and tearDown