如何模拟方法中的对象方法调用？

Question

下面是我想要为以下内容创建一个测试的类和方法：

public class RequestController {    
private GetAllInter getAnalytics;//This is an interface

@RequestMapping(value ="",method=RequestMethod.GET)
public String getAllAnalytics(){
    log.debug("Processing request for all analytics");
    String result;
    try {
        result = getAnalytics.getAll();
    } catch (Exception e) {
        result = "Could not retrieve full list of analytics";
        log.error(result,e);
    }
    return result;
}

具体来说，我希望模拟getAnalytics.getAll()，以便它返回我已经定义的字符串。而不是做它的事情的方法。这是我的密码：

public class RequestControllerTest extends Mockito{

private String allAnalyticsStr = "Hello";

@Test
public void testGetAllAnalytics(){
    GetAllInter getAll = mock(GetAllInter.class);
    when(getAll.getAll()).thenReturn("what");
    RequestController requestController = new RequestController();
    assert(requestController.getAllAnalytics().equals("Hello"));
}

当我尝试运行测试时，这是我得到的错误：

16:17:03.240主调试程序(用于所有分析的处理要求16:17:03.248主要错误dar.RequestController )无法在dar.RequestController.getAllAnalytics(RequestController.java:32) ~classes/:na在dar.RequestControllerTest.testGetAllAnalytics(RequestControllerTest.java:28)测试-classes/:na(在sun.reflect.NativeMethodAccessorImpl.invoke0(Native方法上) ~na:1.7.0_79在sun.reflect上检索分析java.lang.NullPointerException: null的完整列表。.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~na:1.7.0_79 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~na:1.7.0_79 at java.lang.reflect.Method.invoke(Method.java:606) ~na:1.7.0_79 at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) junit-4.12.jar:4.12 at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) junit-4.12.jar:4.12 at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) junit-4.12.jar:4.12 at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) junit-4.12.jar:4.12 at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) junit-4。12.jar:4.12在org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) junit-4.12.jar:4.12 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) junit-4.12.jar:4.12 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) junit-4.12.jar:4.12 at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)junit-4.12.jar:4.12 at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) junit-4.12.jar:4.12 at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) junit-4.12.jar:4.12 at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) junit-4.12.jar:4.12 at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) junit-4.12.jar:4.12在org.junit.runners.ParentRunner.run(ParentRunner.java:363) junit-4.12.jar:4.12在org.junit.runner.JUnitCore.run(JUnitCore.java:137) junit-4.12.jar:4.12在com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117) junit-rt.jar:na在com.intellij.rt.execution.junit.JUnitStarter。( com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74) junit:rt.jar:na在sun.reflect.NativeMethodAccessorImpl.invoke0(Native方法) ~na:1.7.0_79 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~na:1.7.0_79 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~na:1.7java.lang.reflect.Method.invoke(Method.java:606) ~na:1.7.0_79 at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) idea_rt.jar:na和 dar.RequestControllerTest.testGetAllAnalytics(RequestControllerTest.java:28) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) java.lang.reflect.Method.invoke(Method.java:606) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org。junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)，org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)，org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)，org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)，org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)，org.junit.runners.ParentRunner$2。org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74) atsun.reflect.NativeMethodAccessorImpl.invoke0(Native方法)在sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)知道我做错了什么吗？还有别的办法吗？是因为我在嘲笑类的接口而不是类本身吗？

Answer 1

在执行测试之前，您需要用模拟的RequestController#getAnalytics实例替换GetAllInter字段。

GetAllInter getAll = mock(GetAllInter.class);
when(getAll.getAll()).thenReturn("what");

该语句在将RequestController设置为RequestController的字段之前不会影响RequestController的getAnalytics实例行为。

我发现了类似的问题mockito - mocking an interface - throwing NullPointerException

最简单的方法是为RequestController#getAllanalytics提供setter或提供接受GetAllInter参数的RequestController构造函数。

但是使用@InjectMocks将是更好的解决方案，因为您不需要修改RequestController类进行测试。