Java Mockito坚持使用单独方法的doReturn

Question

我有一个单例类来帮助我从控制台读取输入：

public class IOHelper {
    public org.slf4j.Logger logger = Logger.logger;

    //JLine
    public ConsoleReader cr;

    private static IOHelper instance;

    private IOHelper(){
        {
            try {
                cr = new ConsoleReader();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public static synchronized IOHelper getInstance(){
        if (instance == null){
            instance = new IOHelper();
        }

        return instance;
    }

我想测试的代码将其称为：

String in = IOHelper.getInstance().cr.readLine();

然后是我的测试班：

class Test {

    private static NetworkCommunicator networkCommunicator;
    private static IOHelper ioHelper;

    @BeforeAll
    static void setUpClass() throws Throwable {

        ioHelper = spy(IOHelper.getInstance());
        doReturn("1").when(ioHelper).cr.readLine();

        networkCommunicator = spy(NetworkCommunicator.class);

        doNothing().when(networkCommunicator).connectToServer();
        doNothing().when(networkCommunicator).connectToOtherServer();
    }

我的测试卡在doReturn("1").when(ioHelper).cr.readLine();行，就好像它实际执行了cr.readline();部分一样。我的stacktrace指向FileInputStream上找到的方法private native int read0() throws IOException;。评论表明，如果没有可用的输入，它会阻止。 我想在我的控制台上替换方法readLine()，所以当我的CLI请求输入时，我的测试可以“伪造”该输入。

编辑：2个有趣线程的调用堆栈：

"main@1" prio=5 tid=0x1 nid=NA runnable
  java.lang.Thread.State: RUNNABLE
     blocks NonBlockingInputStreamThread@1437
      at java.io.FileInputStream.read0(FileInputStream.java:-1)
      at java.io.FileInputStream.read(FileInputStream.java:207)
      at jline.internal.NonBlockingInputStream.read(NonBlockingInputStream.java:166)
      - locked <0x67d> (a jline.internal.NonBlockingInputStream)
      at jline.internal.NonBlockingInputStream.read(NonBlockingInputStream.java:135)
      at jline.internal.NonBlockingInputStream.read(NonBlockingInputStream.java:243)
      at jline.internal.InputStreamReader.read(InputStreamReader.java:257)
      at jline.internal.InputStreamReader.read(InputStreamReader.java:194)
      at jline.console.ConsoleReader.readCharacter(ConsoleReader.java:2147)
      at jline.console.ConsoleReader.readCharacter(ConsoleReader.java:2137)
      at jline.console.ConsoleReader.readBinding(ConsoleReader.java:2222)
      at jline.console.ConsoleReader.readLine(ConsoleReader.java:2463)
      at jline.console.ConsoleReader.readLine(ConsoleReader.java:2374)
      at jline.console.ConsoleReader.readLine(ConsoleReader.java:2362)
      at jline.console.ConsoleReader.readLine(ConsoleReader.java:2350)
      at com.mypkg.Test.setUpClass(Test.java:43)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-1)
      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.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:389)
      at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:115)
      at org.junit.jupiter.engine.descriptor.ClassTestDescriptor.lambda$invokeBeforeAllMethods$5(ClassTestDescriptor.java:228)
      at org.junit.jupiter.engine.descriptor.ClassTestDescriptor$$Lambda$162.715378067.execute(Unknown Source:-1)
      at org.junit.jupiter.engine.execution.ThrowableCollector.execute(ThrowableCollector.java:40)
      at org.junit.jupiter.engine.descriptor.ClassTestDescriptor.invokeBeforeAllMethods(ClassTestDescriptor.java:227)
      at org.junit.jupiter.engine.descriptor.ClassTestDescriptor.before(ClassTestDescriptor.java:151)
      at org.junit.jupiter.engine.descriptor.ClassTestDescriptor.before(ClassTestDescriptor.java:61)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.lambda$execute$3(HierarchicalTestExecutor.java:80)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$$Lambda$134.398690014.execute(Unknown Source:-1)
      at org.junit.platform.engine.support.hierarchical.SingleTestExecutor.executeSafely(SingleTestExecutor.java:66)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:77)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.lambda$null$2(HierarchicalTestExecutor.java:92)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$$Lambda$137.1353170030.accept(Unknown Source:-1)
      at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
      at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
      at java.util.Iterator.forEachRemaining(Iterator.java:116)
      at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
      at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
      at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
      at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
      at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
      at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
      at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.lambda$execute$3(HierarchicalTestExecutor.java:92)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$$Lambda$134.398690014.execute(Unknown Source:-1)
      at org.junit.platform.engine.support.hierarchical.SingleTestExecutor.executeSafely(SingleTestExecutor.java:66)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:77)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:51)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:43)
      at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:170)
      at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:154)
      at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:90)
      at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:62)
      at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
      at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
      at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

"NonBlockingInputStreamThread@1437" daemon prio=5 tid=0xf nid=NA waiting
  java.lang.Thread.State: WAITING
     waiting for main@1 to release lock on <0x67d> (a jline.internal.NonBlockingInputStream)
      at java.lang.Object.wait(Object.java:-1)
      at jline.internal.NonBlockingInputStream.run(NonBlockingInputStream.java:275)
      at java.lang.Thread.run(Thread.java:745)

扩展这个问题：我有一些方法要求用户多个输入（例如更新一些设置）。我是否认为最好的方法是将设置重构为接受参数并仅测试此新方法的方法？有没有一个解决方案，我可以将一系列字符串传递给测试，以便在任何方法尝试从ConsoleReader读取时按下？我想过使用Robot但是如果读取不是由测试而不是基础逻辑完成的话，我如何确保以正确的顺序传递击键？

Answer 1

好像你在嘲笑错误的东西。你想要玩ConsoleReader的回报。所以有两个选择：

移动以在getConsoleReader()类上使用一些IOHelper方法，然后您可以模拟出来 - 您需要确保IOHelper类也通过此方法访问此方法。 E.g。

private final IOHelper mySpy = spy(IOHelper.getInstance());

@Before
public void setup() {
    final ConsoleReader mockCR = mock(ConsoleReader.class);
    // Any mockery on your mockCR you need.
    // doReturn(...).when(mockCR).readLine();, etc.
    doReturn(mockCR).when(mySpy).getConsoleReader();
}

将cr字段修改为模拟。 E.g。

private final IOHelper ioHelper= IOHelper.getInstance();

@Before
public void setup() {
    final ConsoleReader mockCR = mock(ConsoleReader.class);
    // Any mockery on your mockCR you need.
    // doReturn(...).when(mockCR).readLine();, etc.
    ioHelper.cr = mockCR;
}

我虽然警告过这个案子;我看不出有理由让您ConsoleReader成为public（或不是final），这只是一个要求。即使它是私有的，你总是可以使用一些帮助程序库来搞乱这个字段。 spring和apache-commons-lang3都提供了这种实用程序。

使用Powermock来摆弄ConsoleReader：

的构造函数

@RunWith(PowerMockRunner.class)
@PrepareForTest(IOHelper.class)
public class IOHelperTest {
    @BeforeClass
    public static void setup() {
        final ConsoleReader mockCR = mock(ConsoleReader.class);
        // Any mockery on your mockCR you need.
        // doReturn(...).when(mockCR).readLine();, etc.

        PowerMock.whenNew(ConsoleReader.class).thenReturn(mockCR);
    }
}

最后，您可以修改IOHelper类以将ConsoleReader作为构造函数参数，并简单地提供上述所有方法中的mockCR（并使其不是private {1}}）。