PowerMock with Mockito doesn't create mock for constructor invocations - mockito

Question

I'm trying to use PowerMock with mockito to create mock each time any constructor of FileOutputStream is created but it seems to return a real instance instead of a mocked one.
My test class :
#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);
}
}
My class under test -
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);
}
}
so when I'm creating the class I'm still getting the null pointer exception which thrown by the real constructor invocation
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 object is instantiated in okio.Okio.sink method.
So, add Okio.class in #prepareForTest.