[[testcontext-ctx-management-javaconfig]]
= Context Configuration with Component Classes

To load an `ApplicationContext` for your tests by using component classes (see
xref:core/beans/java.adoc[Java-based container configuration]), you can annotate your test
class with `@ContextConfiguration` and configure the `classes` attribute with an array
that contains references to component classes. The following example shows how to do so:

[tabs]
======
Java::
+
[source,java,indent=0,subs="verbatim,quotes"]
----
	@ExtendWith(SpringExtension.class)
	// ApplicationContext will be loaded from AppConfig and TestConfig
	@ContextConfiguration(classes = {AppConfig.class, TestConfig.class}) // <1>
	class MyTest {
		// class body...
	}
----
<1> Specifying component classes.

Kotlin::
+
[source,kotlin,indent=0,subs="verbatim,quotes"]
----
	@ExtendWith(SpringExtension::class)
	// ApplicationContext will be loaded from AppConfig and TestConfig
	@ContextConfiguration(classes = [AppConfig::class, TestConfig::class]) // <1>
	class MyTest {
		// class body...
	}
----
<1> Specifying component classes.
======


[[testcontext-ctx-management-javaconfig-component-classes]]
.Component Classes
[TIP]
====
The term "`component class`" can refer to any of the following:

* A class annotated with `@Configuration`.
* A component (that is, a class annotated with `@Component`, `@Service`, `@Repository`, or other stereotype annotations).
* A JSR-330 compliant class that is annotated with `jakarta.inject` annotations.
* Any class that contains `@Bean`-methods.
* Any other class that is intended to be registered as a Spring component (i.e., a Spring
  bean in the `ApplicationContext`), potentially taking advantage of automatic autowiring
  of a single constructor without the use of Spring annotations.

See the javadoc of
{spring-framework-api}/context/annotation/Configuration.html[`@Configuration`] and
{spring-framework-api}/context/annotation/Bean.html[`@Bean`] for further information
regarding the configuration and semantics of component classes, paying special attention
to the discussion of `@Bean` Lite Mode.
====

If you omit the `classes` attribute from the `@ContextConfiguration` annotation, the
TestContext framework tries to detect the presence of default configuration classes.
Specifically, `AnnotationConfigContextLoader` and `AnnotationConfigWebContextLoader`
detect all `static` nested classes of the test class that meet the requirements for
configuration class implementations, as specified in the
{spring-framework-api}/context/annotation/Configuration.html[`@Configuration`] javadoc.
Note that the name of the configuration class is arbitrary. In addition, a test class can
contain more than one `static` nested configuration class if desired. In the following
example, the `OrderServiceTest` class declares a `static` nested configuration class
named `Config` that is automatically used to load the `ApplicationContext` for the test
class:

[tabs]
======
Java::
+
[source,java,indent=0,subs="verbatim,quotes"]
----
	@SpringJUnitConfig <1>
	// ApplicationContext will be loaded from the static nested Config class
	class OrderServiceTest {

		@Configuration
		static class Config {

			// this bean will be injected into the OrderServiceTest class
			@Bean
			OrderService orderService() {
				OrderService orderService = new OrderServiceImpl();
				// set properties, etc.
				return orderService;
			}
		}

		@Autowired
		OrderService orderService;

		@Test
		void testOrderService() {
			// test the orderService
		}

	}
----
<1> Loading configuration information from the nested `Config` class.

Kotlin::
+
[source,kotlin,indent=0,subs="verbatim,quotes"]
----
	@SpringJUnitConfig <1>
	// ApplicationContext will be loaded from the nested Config class
	class OrderServiceTest {

		@Autowired
		lateinit var orderService: OrderService

		@Configuration
		class Config {

			// this bean will be injected into the OrderServiceTest class
			@Bean
			fun orderService(): OrderService {
				// set properties, etc.
				return OrderServiceImpl()
			}
		}

		@Test
		fun testOrderService() {
			// test the orderService
		}
	}
----
<1> Loading configuration information from the nested `Config` class.
======


