java 单元测试方法小结

基本框架

被测类

package com.nokia.imp.domainhandler.AtlHandler;

public class AtlHandler extends Handler {
 private AtlHandler atlHandler;
 private AttachmentMaker attachmentMaker;

  public AtlHandler(Context context) {
    super(context);
    attachmentMaker = new AttachmentMaker();
  }

  @Override
  public void upload(GetRequest getRequest) {
  }
}

测试类

package com.nokia.imp.domainhandler.atlHandler;

public class AtlHandlerTest{
  private static final String VIRTUAL_AGENT_ID1 = "mrbts-1";
  private AttachmentMaker attachmentMakerMock;

  @Before
  public void setUp() throws Exception {
    attachmentMakerMock = mock(AttachmentMaker .class);
    atlHandler = new(...);
  }

  @After
    public void cleanup() {
  }

  @Test
  public void should_doSomeThing_when_givenCondition() {
    // given

    // when

    // then
  }

}

Q1：用 Whitebox 改变 private 成员的值

Whitebox.setInternalState(AtlHandler, "auditTrailLogUploadTasks", auditTrailLogUploadTasks);

表示将AtlHandler类中名字为 “auditTrailLogUploadTasks” 的变量赋值为 auditTrailLogUploadTasks；

现有这样一个例子：
在被测类 AtlHandler 中, 有一个SubscribedObjectsChangedManager 类型的 private 成员，这个成员在构造函数中被初始化。现在需要改变的是SubscribedObjectsChangedManager这个类的private 成员 Service，可以这么做：

Object manager = Whitebox.getInternalState(troubleShootHandler, "subscribedObjectsChangedManager");
Whitebox.setInternalState(manager, "service", service);

表示先将 AtlHandler 类中名为 “subscribedObjectsChangedManager” 的private成员取出来，取名为manager，再将manager这个成员类里面名为“service”的成员取出来，赋上我们构建的 service；

service可以是真实对象，也可以是mock或者spy的对象。mock的对象无法调用到真实的方法。而spy出来的类是真实的，并且可以使里面的方法返回你想要的值：

Service service = spy(new Service());
Whitebox.setInternalState(objectsChangedManager, "service", service);
doReturn("ute").when(service).getName(anyString());

当service调用getName方法时返回“ute”字符串；

Q2：如何mock被测类中new出来的类

如果 new 出来的类是在构造函数中赋给了被测类中的 private 变量，则可以参考Q1的方法；
如果在代码中使用到了 new 方法，那就只能采用 PowerMock；
首先要在测试类前面加上如下note：

@RunWith(PowerMockRunner.class)
@PrepareForTest({FeedbackMessageMaker.class, AtlHandler.class})
public class AtlHandlerTest {
}

private AttachmentMaker attachmentMaker;
attachmentMaker = mock(AttachmentMaker.class);
whenNew(AttachmentMaker.class).withAnyArguments().thenReturn(attachmentMaker);
when(attachmentMaker.asFeedbackAttachment().thenReturn(attachment));
verify(attachmentMaker, times(1)).asFeedbackAttachment();

Q3：如何在测试中获取局部变量的值？

如需要验证 StatusReport 的内容，我们可以这样做：

ArgumentCaptor reportCaptor = ArgumentCaptor.forClass(StatusReport.class);
verify(statusReportSender,times(1)).accept(reportCaptor.capture());
verify(orchestratorMock).updateNeInfomodel(updateCaptor.capture());
StatusReport report = reportCaptor.getValue();
assertTrue(report.isCompleted());
assertEquals(virtualAgentId, report.getVirtualAgentId());

Q4: 如何mock static?

PowerMockito.mockStatic(BufferManager.class); 

Q5: 如何测试代码中抛出来的exception

@Test(expected = CmConfigException.class)

Q6:验证测试结果

assertEquals(TroubleShootTestUtils.OPERATIONID_1, statusReport.getOperationId());
assertTrue(statusReport.getContent().contains(TroubleShootErrorText.OPERATION_CONFLICT));
verify(handlerExecutorMock).submit(Matchers.isA(TroubleShootTask.class));
verify(provisionRequestManager, times(1)).onReceiveProvisionRequest(eq(setRequest));

Q7:异步代码测试

public class SnapshotTransferToLssTask extends SftpTask implements ElementTask {}
public class SnapshotTransferInfoUpdateTask implements BiConsumer {}
...
SnapshotTransferToLssTask task = new SnapshotTransferToLssTask(neId, lssConfig, priKeyPath, zipFilePath, service);
CompletableFuture transfer = handler.getExecutor().submit(task);
transfer.whenCompleteAsync(new SnapshotTransferInfoUpdateTask(service));

在这里，异步体现在只有当task里的事情做完了之后才创建 SnapshotTransferInfoUpdateTask, 再执行里面的任务。

CountDownLatch countDown = new CountDownLatch(1);
doAnswer(releaseLatch(countDown)).when(service).stopOperation(any());
troubleShootHandler.onObjectsChanged(genericInfomodelUpdate);
countDown.await(2, TimeUnit.SECONDS);

只有当stopOperation这个方法被调用到才会退出case，否则就等待，等待时间最长2秒;

// given
when(snapshotHandler.getSnapshotUploadExecutor()).thenReturn(handlerExecutorMock);   when(handlerExecutorMock.submit(any())).thenReturn(CompletableFuture.completedFuture(""));
 // when
snapshotCollectionTask.get();
 // then
verify(handlerExecutorMock).submit(Matchers.isA(SnapshotTransferToLssTask.class));

只能验证到 submit函数传进去的参数是 SnapshotTransferToLssTask.class；

private Answer releaseLatch(CountDownLatch latch) {
  return invocation -> {
    latch.countDown();
    return null;
  };
}  

Q8:创建路径

Files.createDirectories(Paths.get("../bin/check_trace_port.sh"));
Files.deleteIfExists(Paths.get("../bin/check_trace_port.sh"));