Spring Framework Testing Concepts
External
Internal
Overview
Proper deployment of dependency injection makes both unit and integration testing easier, in that the presence of setter methods and appropriate constructors on classes makes them easier to wire together in a test without having to set up service locator registries or similar structures.
Unit Tests
According to Spring reference documentation, a Spring unit test is a test that does not use a real application context. The unit test should work without such a real application context, and use objects created with the new operator and injected with a direct invocation of the constructor or setter methods.
Spring provides MockEnvironment and MockPropertySource that are useful for developing out-of-container tests. Understand this.
Integration Tests
According to Spring reference documentation, a Spring integration test is a test where dependencies are injected with the help of a real application context, albeit a special, test-oriented implementation of it. Yet, these tests do not rely on the presence of an application server or Spring Boot instance, or a deployment environment. These tests are slower to run than unit tests, but much faster than the equivalent Selenium or remote tests, that rely on deployment in an actual deployment environment.
Spring provides an integration testing framework, named Spring TestContext Framework. The framework is annotation-driven, and aims to provide the following:
- Context management and caching between tests. This generally speeds up successive tests.
- Dependency injection of test fixture instances.
- Transaction management. The tests can be coded assuming existence of a transaction.
- Spring-specific base classes.
Spring TestContext Framework Dependency
dependencies {
testImplementation('org.springframework:spring-test')
}
This dependency declaration assumes that we are using Gradle Spring dependency-management Plugin and a Maven BOM.
Integration Test Programming Model
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@ContextConfiguration(classes = {AComponent.class})
public class AComponentIntegrationTests {
@Autowired
private AComponent aComponent;
@Test
public void realContextInjectsComponent() {
assertNotNull(aComponent);
}
}