PowerMock with Mockito 不会为构造函数调用创建模拟

Question

我试图将PowerMock与Mockito一起使用，每次创建FileOutputStream的任何构造函数时都创建模拟，但似乎返回真实实例而不是模拟的实例。

我的测试课：

@RunWith(PowerMockRunner.class)
@PrepareForTest({FileOutputStream.class,FilesHelper.class})
public class FilesHelperTest {

@Test
public void createFileFromInputStream_validate_null_progress_subject_doesnt_throws_null_pointer() throws Exception {
    FileOutputStream fileOutputStream = Mockito.mock(FileOutputStream.class);
    PowerMockito.whenNew(FileOutputStream.class).withAnyArguments().thenReturn(fileOutputStream);
    File file = Mockito.mock(File.class);
    BufferedSource bufferedSource = Mockito.mock(BufferedSource.class);
    Mockito.doReturn(true).when(file).exists();
    Mockito.when(bufferedSource.read(Mockito.any(),Mockito.anyLong())).thenReturn(15L,-1L);
    FilesHelper.createFileFromInputStream(file,bufferedSource,8,null);
 }
}

我正在测试的课程 -

public class FilesHelper {
/**
 * Creates a file out of an input stream wrapped by Okio's {@link BufferedSource}.
 * @param file a file to save the input to
 * @param bufferedSource the source input.
 * @param maxSize the maximum amount of bytes can be loaded to memory
 * @param progressUpdatePublisher an optional update publisher which notifies the writing progress
 * @return a {@link com.bonimoo.wominstaller.data.entities.BaseDownloadStatusDTO.Done} status with all the necessary information.
 * @throws IOException in case of errors while writing
 * @throws IllegalStateException when the file doesn't exists and cannot be created
 */
public static BaseDownloadStatusDTO.Done createFileFromInputStream(File file, BufferedSource bufferedSource, int maxSize, @Nullable PublishSubject<BaseDownloadStatusDTO> progressUpdatePublisher) throws IOException, IllegalStateException {
    if (!file.exists()) {
        Throwable cause = null;
        boolean created = false;
        try {
            created = file.createNewFile();
        } catch (IOException e) {
            cause = e;
        }
        if (!created) {
            throw new IllegalStateException("FilesHelper cannot create new file",cause);
        }
    }
    if (progressUpdatePublisher != null) {
        progressUpdatePublisher.onNext(new BaseDownloadStatusDTO.Started(file.getAbsolutePath()));
    }
    BufferedSink sink = Okio.buffer(Okio.sink(file));
    Buffer buffer = new Buffer();
    long counter = 0L;
    try {
        for (long readCount = bufferedSource.read(buffer, maxSize); readCount > -1 || bufferedSource.exhausted(); readCount = bufferedSource.read(buffer, maxSize)) {
            sink.writeAll(buffer);
            counter += readCount;
            if (progressUpdatePublisher != null) {
                progressUpdatePublisher.onNext(new BaseDownloadStatusDTO.Progress(counter,file.getAbsolutePath(),readCount));
            }
        }
    } finally {
        sink.flush();
        sink.close();
        buffer.close();
        bufferedSource.close();
    }
    return new BaseDownloadStatusDTO.Done(file);
 }
}

因此，当我创建类时，我仍会获得由真实构造函数调用

抛出的空指针异常

java.lang.NullPointerException
    at java.io.FileOutputStream.<init>(FileOutputStream.java:203)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:162)
    at okio.Okio.sink(Okio.java:181)
    at com.bonimoo.wominstaller.data.helpers.FilesHelper.createFileFromInputStream(FilesHelper.java:49)
    at com.bonimoo.wominstaller.data.helpers.FilesHelperTest.createFileFromInputStream_validate_null_progress_subject_doesnt_throws_null_pointer(FilesHelperTest.java:36)
    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.internal.runners.TestMethod.invoke(TestMethod.java:68)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:326)
    at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:89)
    at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:97)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.executeTest(PowerMockJUnit44RunnerDelegateImpl.java:310)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTestInSuper(PowerMockJUnit47RunnerDelegateImpl.java:131)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.access$100(PowerMockJUnit47RunnerDelegateImpl.java:59)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner$TestExecutorStatement.evaluate(PowerMockJUnit47RunnerDelegateImpl.java:147)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.evaluateStatement(PowerMockJUnit47RunnerDelegateImpl.java:107)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTest(PowerMockJUnit47RunnerDelegateImpl.java:82)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runBeforesThenTestThenAfters(PowerMockJUnit44RunnerDelegateImpl.java:298)
    at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:87)
    at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:50)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.invokeTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:218)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.runMethods(PowerMockJUnit44RunnerDelegateImpl.java:160)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$1.run(PowerMockJUnit44RunnerDelegateImpl.java:134)
    at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:34)
    at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:44)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.run(PowerMockJUnit44RunnerDelegateImpl.java:136)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:117)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:57)
    at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:59)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Answer 1

fileOutputstream对象是在okio.okio.sink方法中实例化的。

所以，在@preparefortest中添加okio.class。