What Is Integration Testing?

Integration testing checks how different parts of your application work together as a whole. Unlike unit testing, which focuses on testing one class or method in isolation, integration testing ensures that components interact correctly — including your database, web controllers, services, and external systems.

Why Integration Testing Matters in Spring Boot

Spring Boot applications often rely on multiple layers, such as controllers, services, and repositories. These layers use Spring’s dependency injection to collaborate. Integration testing is important because it:

• Verifies that components work together as expected;
• Catches configuration problems, such as missing beans or incorrect application properties;
• Ensures that real-world scenarios, like saving data to a database, actually work;
• Reduces the risk of bugs escaping into production.

Integration Testing vs. Unit Testing

• Unit testing checks a single class or method in isolation, mocking dependencies. You use libraries like JUnit and Mockito for unit tests.
• Integration testing checks how multiple components interact, using real or test implementations of dependencies. In Spring Boot, you commonly use @SpringBootTest to load the full application context.