Junit：如何覆盖 CompletableFuture 代码

Question

我是 Junit 新手，最近遇到了这个问题。无论我在代码中使用 CompletableFuture，我都无法编写测试用例。就像下面的Java文件一样

更新

审计服务.java

@Autowired
Executor existingThreadPool;

@Override
public void auditData(List<ErrorDetails> alertList) {
    CompletableFuture.runAsync(() -> {
        if (alertList.isEmpty())
            //privateMethodCall1
        else
           //privateMethodCall2
    }, existingThreadPool);
}

我点击此链接并尝试了下面的解决方案，但仍然出现 NPE for CompletableFuture 类似下面的错误。

审计服务测试.java

@InjectMock
AuditService auditService;

@Mock
private CompletableFuture<Void> completableFuture = null;

@Before
public void setup() {
    MockitoAnnotations.initMocks(this);
    completableFuture = CompletableFuture.runAsync(new Runnable() {
        @Override
        public void run() {}
    },Executors.newSingleThreadExecutor());
}

@Test
public void shouldAuditData() {
    List<ErrorDetails> alertList = new ArrayList();
    auditService.auditData(alertList);
}

错误

java.lang.NullPointerException
    at java.util.concurrent.CompletableFuture.screenExecutor(CompletableFuture.java:415)
    at java.util.concurrent.CompletableFuture.runAsync(CompletableFuture.java:1858)
    at com.service.impl.AuditService.auditData(AuditService.java:15)
    at com.service.impl.AuditServiceTest.shouldAuditData(AuditServiceTest.java:249)
    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.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    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.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:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

Answer 1

您需要测试您的逻辑，并且不需要模拟静态方法CompletableFuture.runAsync(...)。因此，您的测试应该看起来像普通测试，但您需要等待一段时间才能确保执行异步代码，因为它不是在同一个线程中执行。因此，目前我将为您提供一个可以使用的示例，Thread.sleep()这不是一个好的约定，在附加问题中您可以询问如何避免使用Thread.sleep().

import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.junit.MockitoJUnitRunner;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

@RunWith(MockitoJUnitRunner.class)
public class AuditServiceTest {

    @Mock
    Service serviceMock;

    @Test
    public void shouldAuditData() {
        AuditService auditService = new AuditService(serviceMock);
        List<Object> alertList = new ArrayList();
        auditService.auditData(alertList);
        // you can wait with Thread.sleep() 
        // because the execution is asynchronous
        Mockito.verify(serviceMock).method1();
        Mockito.verify(serviceMock, Mockito.never()).method2();
    }
}

class AuditService {

    Executor existingThreadPool = Executors.newSingleThreadExecutor();
    Service service;

    public AuditService(Service service) {
        this.service = service;
    }

    public void auditData(List<Object> alertList) {
        CompletableFuture.runAsync(() -> {
            if (alertList.isEmpty()) {
                service.method1();
            } else {
                service.method2();
            }
        }, existingThreadPool);
    }
}
class Service {
    public void method1(){};
    public void method2(){};
}