UnitTest, Mock整数类型返回NPE（null）报错

我会带着你远行 2023-07-03 07:02 82阅读 0赞

在Mock整数数据的时候，如果是使用any（）则报如下错误。需要使用anyInt（）。报错如下，具体分析参考下文：

java.lang.NullPointerException
    	at xxx.WtfTest.testCaseNPE(WtfTest.java:34)
    	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.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.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    	at org.mockito.internal.runners.SilentJUnitRunner.run(SilentJUnitRunner.java:39)
    	at org.mockito.internal.runners.StrictRunner.run(StrictRunner.java:39)
    	at org.mockito.junit.MockitoJUnitRunner.run(MockitoJUnitRunner.java:103)
    	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
    	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:237)
    	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
    
    
    You cannot use argument matchers outside of verification or stubbing.
    Examples of correct usage of argument matchers:
        when(mock.get(anyInt())).thenReturn(null);
        doThrow(new RuntimeException()).when(mock).someVoidMethod(anyObject());
        verify(mock).someMethod(contains("foo"))
    
    Also, this error might show up because you use argument matchers with methods that cannot be mocked.
    Following methods *cannot* be stubbed/verified: final/private/equals()/hashCode().
    Mocking methods declared on non-public parent classes is not supported.

具体分析：

带有的签名`any()`，`javac`认为

*  其`any()`可以返回`Integer`=>插入的期望是整数
 *  该`Integer`可以是装箱=>调用`intValue`

然而 `any`

*  返回类型`T`的隐式上限为`Object`=> `Integer`匹配`javac`
 *  返回`null`引用=>确定`Integer`

NPE是通过未明确编写的代码在上引发的，我们在这里实际上不能做任何事情。注意`any() ` 的javadoc 使用原始变量：

For primitive types use {@link #anyChar()} family...