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Elizaveta
Asked:2022-02-08 18:08:43 +0800 CST2022-02-08 18:08:43 +0800 CST

@Mock 抛出 NullPointerException

  • 772

我正在尝试编写一个测试方法，但它失败了 - Junit 没有看到@ExtendWith(MockitoExtension.class)它，或者我做错了其他事情：

@ExtendWith(MockitoExtension.class)
class CategoryRepositoryImplTest {

    @Mock
    private static CategoryScanner categoryScanner;

    @InjectMocks
    private CategoryRepository repository;

    @BeforeAll
    static void setMockBehavior() {
         //Валится на след строчке!!
        when(categoryScanner.scanCategories(anyString())).thenReturn(List.of( //<------- На этой
               new ClothesCategory(),
               new ToysCategory(),
               new FoodCategory()
        ));
    }

    @Test
    void findAll() {

        List<Category> expectedCategories = categoryScanner.scanCategories("");
        List<Category> actualCategories = repository.findAll();

        assertEquals(expectedCategories, actualCategories);
    }
}

这是他写的：

Test ignored.

java.lang.NullPointerException
    at coherentsolutions.nastyabakhshieva.repositories.impl.CategoryRepositoryImplTest.setMockBehavior(CategoryRepositoryImplTest.java:34)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:688)
    at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
    at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
    at org.junit.jupiter.engine.extension.TimeoutExtension.interceptLifecycleMethod(TimeoutExtension.java:126)
    at org.junit.jupiter.engine.extension.TimeoutExtension.interceptBeforeAllMethod(TimeoutExtension.java:68)
    at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeBeforeAllMethods$9(ClassBasedTestDescriptor.java:384)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.invokeBeforeAllMethods(ClassBasedTestDescriptor.java:382)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.before(ClassBasedTestDescriptor.java:196)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.before(ClassBasedTestDescriptor.java:78)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:136)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1380)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:96)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:75)
    at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
    at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
    at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220)
    at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53)

一定是没有创建模拟对象（但不完全是）。如何纠正？

另一方面，如果这样重写：

@Mock
    private static CategoryScanner categoryScanner;

    @InjectMocks
    private CategoryRepositoryImpl repository;

    @BeforeAll
    static void setMockBehavior() {
        categoryScanner = mock(CategoryScanner.class);

        when(categoryScanner.scanCategories(anyString())).thenReturn(List.of(
               new ClothesCategory(),
               new ToysCategory(),
               new FoodCategory()
        ));
    }

这不会破坏任何东西，但是注释不应该@ExtendWith(MockitoExtension.class)为我创建模拟对象的实例吗？

java

1 个回答

  1. Best Answer

    也许这个问题的答案会帮助你https://stackoverflow.com/questions/65543399/mockito-does-not-initialize-mock-in-test-running-with-junit-5-in-beforeall-anno

    更具体地说，答案是：MockitoExtension 类实现了 BeforeEachCallback，但没有实现来自 JUnit-Jupiter-API 的 BeforeAllCallback。因此，它不为 @BeforeAll 注释方法提供任何额外的行为。

    如果你在行上放一个断点

    when(categoryScanner.scanCategories(anyString())).thenReturn(List.of(

    在你的第一个代码中，你可以看到 categoryScanner 为空，但是如果你注释掉 setMockBehavior 方法并在 findAll() 方法中放置一个断点，categoryScanner 对象会被 hocking，提示调用了 @BeforeAll 注解的 setMockBehavior 方法在 @Mock 注释如何工作之前

    • 1

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