Auto-configured Spring WebFlux Tests

To test that Spring WebFlux controllers are working as expected, you can use the @WebFluxTest annotation. @WebFluxTest auto-configures the Spring WebFlux infrastructure and limits scanned beans to @Controller, @ControllerAdvice, @JsonComponent, Converter, GenericConverter, WebFilter, and WebFluxConfigurer. Regular @Component and @ConfigurationProperties beans are not scanned when the @WebFluxTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configurations that are enabled by @WebFluxTest can be found in the appendix.

If you need to register extra components, such as Jackson Module, you can import additional configuration classes using @Import on your test.

Often, @WebFluxTest is limited to a single controller and used in combination with the @MockBean annotation to provide mock implementations for required collaborators.

@WebFluxTest also auto-configures WebTestClient, which offers a powerful way to quickly test WebFlux controllers without needing to start a full HTTP server.

You can also auto-configure WebTestClient in a non-@WebFluxTest (such as @SpringBootTest) by annotating it with @AutoConfigureWebTestClient. The following example shows a class that uses both @WebFluxTest and a WebTestClient:

Java
Kotlin

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.http.MediaType;
import org.springframework.test.web.reactive.server.WebTestClient;

import static org.mockito.BDDMockito.given;

@WebFluxTest(UserVehicleController.class)
class MyControllerTests {

	@Autowired
	private WebTestClient webClient;

	@MockBean
	private UserVehicleService userVehicleService;

	@Test
	void testExample() {
		given(this.userVehicleService.getVehicleDetails("sboot"))
			.willReturn(new VehicleDetails("Honda", "Civic"));
		this.webClient.get().uri("/sboot/vehicle").accept(MediaType.TEXT_PLAIN).exchange()
			.expectStatus().isOk()
			.expectBody(String.class).isEqualTo("Honda Civic");
	}

}

import org.junit.jupiter.api.Test
import org.mockito.BDDMockito.given
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest
import org.springframework.boot.test.mock.mockito.MockBean
import org.springframework.http.MediaType
import org.springframework.test.web.reactive.server.WebTestClient
import org.springframework.test.web.reactive.server.expectBody

@WebFluxTest(UserVehicleController::class)
class MyControllerTests(@Autowired val webClient: WebTestClient) {

	@MockBean
	lateinit var userVehicleService: UserVehicleService

	@Test
	fun testExample() {
		given(userVehicleService.getVehicleDetails("sboot"))
			.willReturn(VehicleDetails("Honda", "Civic"))
		webClient.get().uri("/sboot/vehicle").accept(MediaType.TEXT_PLAIN).exchange()
			.expectStatus().isOk
			.expectBody<String>().isEqualTo("Honda Civic")
	}

}

This setup is only supported by WebFlux applications as using WebTestClient in a mocked web application only works with WebFlux at the moment.

@WebFluxTest cannot detect routes registered through the functional web framework. For testing RouterFunction beans in the context, consider importing your RouterFunction yourself by using @Import or by using @SpringBootTest.

@WebFluxTest cannot detect custom security configuration registered as a @Bean of type SecurityWebFilterChain. To include that in your test, you will need to import the configuration that registers the bean by using @Import or by using @SpringBootTest.

Sometimes writing Spring WebFlux tests is not enough; Spring Boot can help you run full end-to-end tests with an actual server.