Spring Reactive Test case fails to start the Netty Server

Question

I have spring test-case as shown below when I run it is not starting the Netty server and provides following exception.

Caused by: org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:155)

Below is my test case:

@RunWith(SpringRunner.class)
@SpringBootTest(classes = SpringWebFluxDemoApplication.class, webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)
public class CustomPriceControllerTest {

    @Autowired
    private ApplicationContext context;

    private WebTestClient testClient;

    @Before
    public void init() {
        testClient = WebTestClient.bindToApplicationContext(context).configureClient().baseUrl("http://localhost:8080").responseTimeout(Duration.ofSeconds(30)).build();
    }

    @Test
    public void broadcastVoltageConsumption() {

        this.testClient.get().uri("/api/getCustomPrice")
                .accept(MediaType.APPLICATION_STREAM_JSON)
                .exchange()
                .expectBodyList(Custom.class)
                .consumeWith((customResults) -> {
                    List<Custom> list = CustomResults.getResponseBody();
                    Assert.assertTrue(list != null && list.size() > 0);
                });
    }
}

My pom.xml has excluded the dependency for tomcat to enable Netty. My Spring boot class works perfectly fine. It boots Netty server.

Update - pom.xml

 <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-rest</artifactId>
            <exclusions>
                <!-- Exclude the Tomcat dependency -->
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

Had to add javax.servlet-api because I was facing issues with javax.servlet-api missing.

Update - 2 Removing the javax.servlet dependency from pom.xml solves the issue.

While when I try to run my main application it starts the Netty server normally. What is missing in this configuration? Can anyone help on this?

Answer 1

You wanted the webserver to be powered by Netty, but the exception you are getting is Servlet Specific

Since Netty is not servlet based technology, it seems you that somewhere (gradle/maven/@Configuration) you are mixing them, so , just remove all references to Servlet dependencies and re try