Question

我在StackOverflow上研究了类似的问题，但无法找到根本原因。

上下文：

我在@RestController中有SpringBoot 2，并且依赖于BookSearcherService。我想模拟BookSearcherService以便对控制器进行单元测试。

错误：

org.springframework.web.util.NestedServletException：请求处理失败；嵌套的异常是java.lang.NullPointerException 在 org.springframework.web.servlet.FrameworkServlet.processRequest（FrameworkServlet.java:1013）在 org.springframework.web.servlet.FrameworkServlet.doGet（FrameworkServlet.java:897）在javax.servlet.http.HttpServlet.service（HttpServlet.java:634）在 org.springframework.web.servlet.FrameworkServlet.service（FrameworkServlet.java:882）在 org.springframework.test.web.servlet.TestDispatcherServlet.service（TestDispatcherServlet.java:71）在javax.servlet.http.HttpServlet.service（HttpServlet.java:741）处 org.springframework.mock.web.MockFilterChain $ ServletFilterProxy.doFilter（MockFilterChain.java:166）在 org.springframework.mock.web.MockFilterChain.doFilter（MockFilterChain.java:133）在 org.springframework.web.filter.RequestContextFilter.doFilterInternal（RequestContextFilter.java:99）在 org.springframework.web.filter.OncePerRequestFilter.doFilter（OncePerRequestFilter.java:107）在 org.springframework.mock.web.MockFilterChain.doFilter（MockFilterChain.java:133）在 org.springframework.web.filter.FormContentFilter.doFilterInternal（FormContentFilter.java:92）在 org.springframework.web.filter.OncePerRequestFilter.doFilter（OncePerRequestFilter.java:107）在 org.springframework.mock.web.MockFilterChain.doFilter（MockFilterChain.java:133）在 org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal（HiddenHttpMethodFilter.java:93）在 org.springframework.web.filter.OncePerRequestFilter.doFilter（OncePerRequestFilter.java:107）在 org.springframework.mock.web.MockFilterChain.doFilter（MockFilterChain.java:133）在 org.springframework.test.web.servlet.MockMvc.perform（MockMvc.java:182）在 com.search.book.Booksearcher.controller.BookSearcherControllerMockMvcTest.canListAll（BookSearcherControllerMockMvcTest.java:54）在sun.reflect.NativeMethodAccessorImpl.invoke0（本机方法）处 sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:62）在 sun.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）在java.lang.reflect.Method.invoke（Method.java:498）在 org.junit.platform.commons.util.ReflectionUtils.invokeMethod（ReflectionUtils.java:532）在 org.junit.jupiter.engine.execution.ExecutableInvoker.invoke（ExecutableInvoker.java:115）在 org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda $ invokeTestMethod $ 6（TestMethodTestDescriptor.java:171）在 org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute（ThrowableCollector.java:72）在 org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod（TestMethodTestDescriptor.java:167）在 org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute（TestMethodTestDescriptor.java:114）在 org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute（TestMethodTestDescriptor.java:59）在 org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda $ executeRecursively $ 4（NodeTestTask.java:108）在 org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute（ThrowableCollector.java:72）在 org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively（NodeTestTask.java:98）在 org.junit.platform.engine.support.hierarchical.NodeTestTask.execute（NodeTestTask.java:74）在java.util.ArrayList.forEach（ArrayList.java:1257）在 org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll（SameThreadHierarchicalTestExecutorService.java:38）在 org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda $ executeRecursively $ 4（NodeTestTask.java:112）在 org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute（ThrowableCollector.java:72）在 org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively（NodeTestTask.java:98）在 org.junit.platform.engine.support.hierarchical.NodeTestTask.execute（NodeTestTask.java:74）在java.util.ArrayList.forEach（ArrayList.java:1257）在 org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll（SameThreadHierarchicalTestExecutorService.java:38）在 org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda $ executeRecursively $ 4（NodeTestTask.java:112）在 org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute（ThrowableCollector.java:72）在 org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively（NodeTestTask.java:98）在 org.junit.platform.engine.support.hierarchical.NodeTestTask.execute（NodeTestTask.java:74）在 org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit（SameThreadHierarchicalTestExecutorService.java:32）在 org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute（HierarchicalTestExecutor.java:57）在 org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute（HierarchicalTestEngine.java:51）在 org.junit.platform.launcher.core.DefaultLauncher.execute（DefaultLauncher.java:220）在 org.junit.platform.launcher.core.DefaultLauncher.lambda $ execute $ 6（DefaultLauncher.java:188）在 org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams（DefaultLauncher.java:202）在 org.junit.platform.launcher.core.DefaultLauncher.execute（DefaultLauncher.java:181）在 org.junit.platform.launcher.core.DefaultLauncher.execute（DefaultLauncher.java:128）在 org.eclipse.jdt.internal.junit5.runner.JUnit5TestReference.run（JUnit5TestReference.java:89）在 org.eclipse.jdt.internal.junit.runner.TestExecution.run（TestExecution.java:41）在 org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests（RemoteTestRunner.java:541）在 org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests（RemoteTestRunner.java:763）在 org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run（RemoteTestRunner.java:463）在 org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main（RemoteTestRunner.java:209）由以下原因引起：java.lang.NullPointerException com.search.book.Booksearcher.controller.BookSearcherController.listAll（BookSearcherController.java:31）在sun.reflect.NativeMethodAccessorImpl.invoke0（本机方法）处 sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:62）在 sun.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）在java.lang.reflect.Method.invoke（Method.java:498）在 org.springframework.web.method.support.InvocableHandlerMethod.doInvoke（InvocableHandlerMethod.java:189）在 org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest（InvocableHandlerMethod.java:138）在 org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle（ServletInvocableHandlerMethod.java:102）在 org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod（RequestMappingHandlerAdapter.java:892）在 org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal（RequestMappingHandlerAdapter.java:797）在 org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle（AbstractHandlerMethodAdapter.java:87）在 org.springframework.web.servlet.DispatcherServlet.doDispatch（DispatcherServlet.java:1038）在 org.springframework.web.servlet.DispatcherServlet.doService（DispatcherServlet.java:942）在 org.springframework.web.servlet.FrameworkServlet.processRequest（FrameworkServlet.java:1005） ...还有59个

代码：

BookSearcherController.java：

@RestController
@RequestMapping("/book")
@RequiredArgsConstructor
public class BookSearcherController {

    private BookSearcherService bookSearcherService;

    @GetMapping(path = "/list", produces = { "application/json" })
    @ResponseBody
    public List<BookDto> listAll() {
        return bookSearcherService.listAll();
    }
}

BookSearcherService.java：

@Service
public class BookSearcherService {

    private BookSearcherCrudService bookSearcherCrudService;

    @Autowired
    void setBookSearcherRepository(BookSearcherCrudService bookSearcherCrudService) {
        this.bookSearcherCrudService = bookSearcherCrudService;
    }

    private BookSearcherRepository bookSearcherRepository;

    @Autowired
    void setBookSearcherRepository(BookSearcherRepository bookSearcherRepository) {
        this.bookSearcherRepository = bookSearcherRepository;
    }

    public List<BookDto> listAll() {
        List<Book> books = bookSearcherRepository.findAll();
        return books.stream()
                .map(bookSearcherCrudService::toDto)
                .collect(Collectors.toList());
    }
}

BookSearcherControllerMockMvcTest.java：

@WebMvcTest(controllers = BookSearcherController.class)
public class BookSearcherControllerMockMvcTest {

    @Autowired
    private MockMvc mockMvc;

    @MockBean
    private BookSearcherService bookSearcherService;

    @Autowired
    private ObjectMapper objectMapper;

    @Test
    public void canListAll() throws Exception {
        assertThat(bookSearcherService).isNotNull();
        assertThat(mockMvc).isNotNull();

        List<BookDto> books = asList(new BookDto("Title 1"), new BookDto("Title 2"), new BookDto("Title 3"));

        given(bookSearcherService.listAll()).willReturn(books);

        ResultActions perform = mockMvc.perform(get("/book/list"));
    }
}

POM.XML

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.search.book</groupId>
    <artifactId>book-searcher</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>book-searcher</name>
    <description>Project for books search</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.flywaydb</groupId>
            <artifactId>flyway-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>junit</groupId>
                    <artifactId>junit</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.mockito</groupId>
            <artifactId>mockito-all</artifactId>
            <version>1.9.5</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.platform</groupId>
            <artifactId>junit-platform-launcher</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.platform</groupId>
            <artifactId>junit-platform-runner</artifactId>
            <scope>test</scope>
        </dependency>


    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

问题：

如上所述，问题是BookSearcherService在mockMvc上执行呼叫时有null。这意味着@MockBean不起作用，或者我犯了一个无法在几个小时内发现的错误。我正在使用Java8。

Answer 1

问题在于bookSearcherService不会被注入BookSearchController，因为它使用的是@RequiredArgsConstructor，在这种情况下不会创建正确的构造函数。

@RequiredArgsConstructor文档指出，将使用未初始化的final或@NonNull字段的参数创建构造函数。但是，bookSearcherService都不是，因此不会作为构造函数参数添加。

因此，尽管模拟本身不为null，但它永远不会注入到经过测试的控制器中。

@MockBean不适用于带有JUnit 5和Sping Boot 2的@WebMvcTest吗？

1 个答案: