Spring 5 + JUnit 5：IllegalStateException：未设置 ServletContext

我正在尝试为 Spring 5 运行单元测试。有三个配置文件。

根配置：

@Configuration
@ComponentScan(basePackages = {"ru.example"})
@PropertySource("classpath:/config/app.properties")
public class RootConfig {

    @Bean
    public static PropertySourcesPlaceholderConfigurer placeholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }

}

事务管理器配置：

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories("ru.example.repository")
@EntityScan("ru.example.domain")
public class TransactionManagerConfig {

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() throws PropertyVetoException {
        LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setDataSource(dataSource());
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setGenerateDdl(true);
        entityManagerFactoryBean.setJpaVendorAdapter(vendorAdapter);
        entityManagerFactoryBean.setPackagesToScan("ru.example.domain");
        return entityManagerFactoryBean;
    }

    @Bean
    public JpaTransactionManager transactionManager() throws PropertyVetoException {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory().getObject());
        return transactionManager;
    }

    private DataSource dataSource() throws PropertyVetoException {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass("com.mysql.jdbc.Driver");
        dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/example");
        dataSource.setUser("root");
        dataSource.setPassword("root");
        dataSource.setMaxPoolSize(20);
        dataSource.setMinPoolSize(3);
        dataSource.setMaxStatements(100);
        dataSource.setPreferredTestQuery("SELECT 1");
        dataSource.setTestConnectionOnCheckout(true);
        return dataSource;
    }

}

网络配置：

@Configuration
@EnableWebMvc
@ComponentScan({"ru.example"})
public class WebConfig implements WebMvcConfigurer {

    @Bean
    @SuppressWarnings("unused")
    public ViewResolver viewResolver() {

        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");
        resolver.setExposeContextBeansAsAttributes(true);
        return resolver;
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {

        registry
                .addResourceHandler("/**")
                .addResourceLocations("/");
    }
}

依赖项是（对于 Spring 和 junit）：

testImplementation group: 'org.junit.jupiter', name: 'junit-jupiter-api', version: JUNIT_VERSION
testRuntimeOnly group: 'org.junit.jupiter', name: 'junit-jupiter-engine', version: JUNIT_VERSION
testCompile group: 'org.junit.jupiter', name: 'junit-jupiter-params', version: '5.3.1'
testCompile group: 'org.mockito', name: 'mockito-core', version: '2.22.0'
testCompile group: 'org.springframework', name: 'spring-test', version: SPRING_VERSION
testCompile group: 'org.hamcrest', name: 'hamcrest-library', version: '1.3'
testCompile group: 'com.jayway.jsonpath', name: 'json-path-assert', version: '2.4.0'
compile group: 'org.springframework', name: 'spring-webmvc', version: SPRING_VERSION
compile group: 'org.springframework', name: 'spring-web', version: SPRING_VERSION
compile group: 'org.springframework', name: 'spring-jdbc', version: SPRING_VERSION
compile group: 'org.springframework.boot', name: 'spring-boot-starter-data-jpa', version: '2.0.5.RELEASE'

SPRING_VERSION = '5.1.0.RELEASE'
JUNIT_VERSION = '5.3.1'

应用程序启动并正常运行。我正在尝试创建测试。

@ExtendWith(SpringExtension.class)
@ContextConfiguration(classes = {
        RootConfig.class,
        TransactionManagerConfig.class,
        WebConfig.class
})
class OrderServiceImplTest {

    @Test
    void save() {
    }
}

落入以下堆栈跟踪：

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.web.servlet.HandlerMapping]: Factory method 'resourceHandlerMapping' threw exception; nested exception is java.lang.IllegalStateException: No ServletContext set
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:620)
    ... 94 common frames omitted
Caused by: java.lang.IllegalStateException: No ServletContext set
    at org.springframework.util.Assert.state(Assert.java:73)
    at org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport.resourceHandlerMapping(WebMvcConfigurationSupport.java:486)
    at org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration$$EnhancerBySpringCGLIB$$b4bf2d2e.CGLIB$resourceHandlerMapping$34(<generated>)
    at org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration$$EnhancerBySpringCGLIB$$b4bf2d2e$$FastClassBySpringCGLIB$$d653d6e3.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244)
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363)
    at org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration$$EnhancerBySpringCGLIB$$b4bf2d2e.resourceHandlerMapping(<generated>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154)
    ... 95 common frames omitted

你能告诉我如何使用 JUnit 5 正确运行 Spring 测试，我做错了什么吗？