Unable to start ReactiveWebApplicationContext due to missing ReactiveWebServerFactory bean

Question

I have a new springboot application I am attempting to get started.

The error I receive is

org.springframework.context.ApplicationContextException: Unable to start reactive web server; nested exception is org.springframework.context.ApplicationContextException: Unable to start ReactiveWebApplicationContext due to missing ReactiveWebServerFactory bean.     at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.onRefresh(ReactiveWebServerApplicationContext.java:76) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE] 

src/main/java/bubbleshadow/RootController.java

package bubbleshadow;  import org.springframework.http.HttpStatus; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; import reactor.core.publisher.Mono;  @RestController public class RootController {   public RootController() {    }    @GetMapping("/")   public Mono<HttpStatus> returnOk() {     return Mono.just(HttpStatus.OK);   } } 

src/test/java/test/bubbleshadow/RootControllerTest.java

package test.bubbleshadow; import bubbleshadow.RootController;  import org.junit.jupiter.api.Test; import org.junit.jupiter.api.extension.ExtendWith; import org.springframework.beans.factory.annotation.Autowired; // import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest; import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient; import org.springframework.test.web.reactive.server.WebTestClient; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.test.context.junit.jupiter.SpringExtension; import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;  @ExtendWith(SpringExtension.class) @SpringBootTest(classes=RootController.class, webEnvironment = WebEnvironment.RANDOM_PORT) @AutoConfigureWebTestClient public class RootControllerTest {   @Autowired   WebTestClient webTestClient;    @Test   public void baseRouteShouldReturnStatusOK() {     webTestClient.head().uri("/").exchange().expectStatus().isOk();   } } 

Answer 1

I assume you are using maven to get your dependencies.

I solved the problem by using:

    <dependency>         <groupId>org.springframework.boot</groupId>         <artifactId>spring-boot-starter-webflux</artifactId>         <version>2.0.3.RELEASE</version>     </dependency> 

Instead of:

    <dependency>         <groupId>org.springframework</groupId>         <artifactId>spring-webflux</artifactId>         <version>5.0.7.RELEASE</version>     </dependency> 

Answer 2

Your configuration is not sufficient for reactive tests.

The reactive WebTestClient as well as ReactiveWebApplicationContext need reactive server in the application context. Add annotation @EnableAutoConfiguration to your RootControllerTest and let Spring's do it for you.

The autoconfiguration searches your class path and after find reactive classes and reactive context then create ReactiveWebServerFactory bean.