如何为Java8谓词编写Mockito测试

我使用的是Spring Boot REST和Mockito。如何编写测试用例

错误：

java.lang.NullPointerException
    at java.util.concurrent.ConcurrentHashMap.putVal(ConcurrentHashMap.java:1011)
    at java.util.concurrent.ConcurrentHashMap$KeySetView.add(ConcurrentHashMap.java:4595)
    at com.mastercard.customer.data.management.refdata.service.RegionService.lambda$2(RegionService.java:58)
    at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:174)
    at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
    at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:419)
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
    at com.mastercard.customer.data.management.refdata.service.RegionService.findAllRegions(RegionService.java:49)
    at com.mastercard.customer.data.management.refdata.service.RegionServiceTest.findAllRegions_SuccessTest(RegionServiceTest.java:68)
    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.mockito.internal.runners.DefaultInternalRunner$1$1.evaluate(DefaultInternalRunner.java:44)
    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.DefaultInternalRunner$1.run(DefaultInternalRunner.java:74)
    at org.mockito.internal.runners.DefaultInternalRunner.run(DefaultInternalRunner.java:80)
    at org.mockito.internal.runners.StrictRunner.run(StrictRunner.java:39)
    at org.mockito.junit.MockitoJUnitRunner.run(MockitoJUnitRunner.java:163)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)

代码

1尝试设置您逐个模拟，而不是级联调用：

when(mongoTemplate.query(Department.class)).thenReturn(executableDepartment);
when(executableDepartment).distinct("employees")).thenReturn(distinctDepartment);
when(distinctDepartment.all()).thenReturn(obj);

当然，可执行部门和distinctDepartment也需要模拟

2不要模拟列表界面。向其提供预配置的数据，并允许SUT按原样处理它。Sp模拟应仅在本部分中使用：

mongoTemplate.query(Department.class).distinct("employees").all();

---

所以提供数据的部分。但让实际逻辑按原样运行

此代码不包括return t->seen.addkeyExtractor.applyt；如果！CollectionUtils.isEmptyobj{regions=obj.stream.mape->Region e.filterdistinctByKeyRegion:：getRegionCd.collectCollectors.toList；}。有任何建议的可执行部门和地区部门模拟吗？当返回空值时，为哪一个？是的，这些是空的。obj列表实际上不是空的吗？

when(mongoTemplate.query(Department.class)).thenReturn(executableDepartment);
when(executableDepartment).distinct("employees")).thenReturn(distinctDepartment);
when(distinctDepartment.all()).thenReturn(obj);

mongoTemplate.query(Department.class).distinct("employees").all();