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PowerMock won't mock static method to throw an Exception in a Spring-Boot application

I realize there are many many very similar questions. I've been through all of them and I still cannot make my code work.
I have a service defined in my Spring-Boot application, just like this:
#Service
public class FileStorageService {
private final Path fileStorageLocation;
#Autowired
public FileStorageService(final FileStorageProperties fileStorageProperties) {
//FileStorageProperties is a very simple class that right now just holds one String value
this.fileStorageLocation = Paths.get(fileStorageProperties.getUploadDir())
.toAbsolutePath()
.normalize();
try {
Files.createDirectories(fileStorageLocation);
} catch (IOException e) {
// FileStorageException is my custom, runtime exception
throw new FileStorageException("Failed to create directory for stored files", e);
}
}
}
And I want to test scenario, when directory creation fails and thus I need to mock method Files.createDirectories(). My test class looks like this:
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import java.io.IOException;
import java.nio.file.Files;
#RunWith(PowerMockRunner.class)
#PrepareForTest({Files.class})
public class FileStorageServiceTest {
private static final String UPLOAD_DIR = "uploadDir";
#Test(expected = FileStorageException.class)
public void some_test() throws IOException {
PowerMockito.mockStatic(Files.class);
PowerMockito.when(Files.createDirectories(Mockito.any())).thenThrow(new IOException());
new FileStorageService(createFileStorageProperties());
}
private FileStorageProperties createFileStorageProperties() {
final FileStorageProperties fileStorageProperties = new FileStorageProperties();
fileStorageProperties.setUploadDir(UPLOAD_DIR);
return fileStorageProperties;
}
}
I believe I followed every step from tutorials and questions I've read.
I use:
#RunWith(PowerMockRunner.class),
#PrepareForTest({Files.class}),
PowerMockito.mockStatic(Files.class),
and PowerMockito.when(Files.createDirectories(Mockito.any())).thenThrow(new IOException());.
Still, no exception is thrown during test and it fails. WIll be super thankful for the help, cause I feel I miss something really simple and just cannot see it.

From: https://github.com/powermock/powermock/wiki/Mock-System
Normally you would prepare the class that contains the static methods (let's call it X) you like to mock but because it's impossible for PowerMock to prepare a system class for testing so another approach has to be taken. So instead of preparing X you prepare the class that calls the static methods in X!
Basically, we mock the class's use of the System class, rather than unmockable System class itself.
#PrepareForTest({Files.class})
An alternative, non-Powermock way to do this without mocking any system class would be to create a helper method, #Spy the original class, and mock that helper method specifically to throw the exception.
when(spy.doSomethingWithSystemClasses()).thenThrow(new Exception("Foo");

How execute code after each dynamic test?

There is a test:
package com.cdek.qa_auto.config;
import com.cdek.qa_auto.utils.CdekJUnitListener;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DynamicTest;
import org.junit.jupiter.api.TestFactory;
import org.junit.platform.launcher.Launcher;
import org.junit.platform.launcher.TestExecutionListener;
import org.junit.platform.launcher.core.LauncherFactory;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Stream;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
import static org.junit.jupiter.api.DynamicTest.dynamicTest;
/***
*
*/
#SpringBootTest
public class JUnit5Test {
public JUnit5Test() throws Exception {}
#BeforeEach
public void beforeEach() throws Exception {
Launcher launcher = LauncherFactory.create();
TestExecutionListener listener = new CdekJUnitListener();
launcher.registerTestExecutionListeners(listener);
}
#TestFactory
public Stream<DynamicTest> test() throws Exception {
List<String> list = new ArrayList<>();
list.add("1");
list.add("12");
list.add("123");
list.add("1234");
list.add("12345");
return list.stream().map(item -> (
dynamicTest("test_" + item, () -> {
if ("1".equalsIgnoreCase(item)) {
System.out.println("fail");
fail("fail");
} else if ("12".equalsIgnoreCase(item)) {
assertTrue(false);
} else if ("123".equalsIgnoreCase(item)) {
throw new Exception("msg");
} else {
assertTrue(true);
}
}
)));
}
}
For example, make a screen for fallen tests.
Written implementation of import org.junit.platform.launcher.TestExecutionListener.
Connect so normally did not work. Does not go into executionFinished.
Basis: JUnit5-Maven-SpringBoot
How do execute specific code after each dynamic test?

As stated in the JUnit 5 User Guide:
The execution lifecycle of a dynamic test is quite different than it
is for a standard #Test case. Specifically, there are no lifecycle
callbacks for individual dynamic tests. This means that #BeforeEach
and #AfterEach methods and their corresponding extension callbacks are
executed for the #TestFactory method but not for each dynamic test. In
other words, if you access fields from the test instance within a
lambda expression for a dynamic test, those fields will not be reset
by callback methods or extensions between the execution of individual
dynamic tests generated by the same #TestFactory method.
Thus, you cannot use an #AfterEach method or one of the "after" lifecycle callback extensions (i.e., AfterEachCallback or AfterTestExecutionCallback).
Depending on what you are trying to achieve in your "listener", you may be able to accomplish that in a TestExecutionListener, but you cannot register that from within the test class. See Plugging in your own Test Execution Listener in the User Guide for details.

Powermock/EasyMock: Set expectation on final method that would throw exception

How do I set an expectation on a final method if I can't safely invoke that method at all? PowerMock is supposed to ensure the invocation is mocked, but I can't even get to that stage:
WithFinal.java:
public class WithFinal {
public final void finalMethod() {
throw new RuntimeException();
}
}
CallsFinal.java:
public class CallsFinal {
private WithFinal withFinal;
public CallsFinal(WithFinal withFinal) {
this.withFinal = withFinal;
}
public void callFinal() {
withFinal.finalMethod();
}
}
PowerMockTest.java:
import org.easymock.EasyMock;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.modules.junit4.PowerMockRunner;
import org.powermock.core.classloader.annotations.PrepareForTest;
import static org.powermock.api.easymock.PowerMock.*;
#RunWith(PowerMockRunner.class)
#PrepareForTest(CallsFinal.class)
public class PowerMockTest {
#Test public void testFinal() {
WithFinal mock = createMock(WithFinal.class);
CallsFinal callsFinal = new CallsFinal(mock);
mock.finalMethod();
EasyMock.expectLastCall().atLeastOnce();
replay(mock);
callsFinal.callFinal();
verify(mock);
}
}
I get a RuntimeException on the very first call to mock.finalMethod(), which makes sense, but I thought the whole point of PowerMock was to make this possible?

There was a simple mistake in the test class: instead of #PrepareForTest(CallsFinal.class), it should have been #PrepareForTest(WithFinal.class).
PowerMock only requires that the calling class be prepared for test when mocking a system class from the JRE; otherwise, it's the class to be mocked itself that needs to get prepared.
Finally, I will mention there is another mocking library that can be used here, which I happen to develop: JMockit. With it, the test can be written as:
import org.junit.*;
import mockit.*;
public class JMockitTest {
#Tested CallsFinal callsFinal;
#Injectable WithFinal mock;
#Test public void testFinal() {
new Expectations() {{ mock.finalMethod(); }};
callsFinal.callFinal();
}
}

Using PowerMock, you can mock skip a internal method call instead of direct method call.
For example you want to test callFinal method of CallsFinal class which internally calling finalMethod of WithFinal class. So in this case if you don't want to instantiate WithFinal class then you need to mock WithFinal object to skip internal call for finalMethod.

PowerMock:: [java.lang.IllegalStateException: no last call on a mock available]

To mock a static method powermock giving an exception while expect().
#Test
public void testRegistrarService()
{
mockStatic(IdGenerator.class);
expect(IdGenerator.generateNewId()).andReturn(42L);
long actualId=serTestObj.registerService();
replay(IdGenerator.class);
verify(IdGenerator.class);
assertEquals(42L,actualId);
}
public class ServiceRegistrator
{
public long registerService()
{
long id = IdGenerator.generateNewId();
return id;
}
}
public class IdGenerator
{
public static long generateNewId()
{
return System.currentTimeMillis();
}
}
Exception is:
java.lang.IllegalStateException: no last call on a mock available
at org.easymock.EasyMock.getControlForLastCall(EasyMock.java:521)
at org.easymock.EasyMock.expect(EasyMock.java:499)
at home.powermock.testServiceRegistrator.testRegistrarService(testServiceRegistrator.java:51)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at com.intellij.rt.execution.junit2.JUnitStarter.main(JUnitStarter.java:31)
how to mock staic method,while m using powerMock
i'm using intelliJ idea,how to resolve that exception.

Your code is missing the annotation
#PrepareForTest(IdGenerator.class)

In my case I was missing the following method in my test class
#ObjectFactory
/**
* Configure TestNG to use the PowerMock object factory.
*/
public IObjectFactory getObjectFactory() {
return new org.powermock.modules.testng.PowerMockObjectFactory();
}
Once I added it, I got rid of the "no last call on a mock available" error.

You need to put the replay before the actual call to the method.
EDIT: I think part of the problem may be caused because of your imports. Try not to import static powermock and static easymock (I've found that I often confuse myself and forget which one I need to call replay on).
Try running the following code. If it doesn't run correctly, then it may be because of a problem with the particular version of PowerMock/EasyMock/Junit that you have.
TestClass:
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.easymock.PowerMock;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import static org.easymock.EasyMock.*;
import static org.junit.Assert.*;
#RunWith(PowerMockRunner.class)
#PrepareForTest(IdGenerator.class)
public class TestClass {
#Test
public void testRegistrarService()
{
ServiceRegistrator serTestObj = new ServiceRegistrator();
PowerMock.mockStatic(IdGenerator.class);
expect(IdGenerator.generateNewId()).andReturn(42L);
PowerMock.replay(IdGenerator.class);
long actualId=serTestObj.registerService();
PowerMock.verify(IdGenerator.class);
assertEquals(42L,actualId);
}
}
IdGenerator:
public class IdGenerator {
public static long generateNewId()
{
return System.currentTimeMillis();
}
}
ServiceRegistrator:
public class ServiceRegistrator {
public long registerService()
{
long id = IdGenerator.generateNewId();
return id;
}
}

This question has been here for a long time but I'll try to give to it an aswer to explain what i did to resolve this problem.
First of all you have to use these two annotations:
#RunWith(PowerMockRunner.class)
This annotation let the current test class know what to use to run his tests, this is useful because we can use PowerMockRunner instead of JUnitRunner
#PrepareForTest(IdGenerator.class)
This annotation is used to prepare the class "IdGenerator" to be used in the test, prepare means that we will be able to mock the static methods as we do to the public methods
After added these two annotations we have to be sure we are using the right packages provided by PowerMock:
1) PowerMock:
Import: import org.powermock.api.easymock.PowerMock;
Use: We will use PowerMock to mock (and not only) our static method with the following code line
PowerMock.mockStatic(IdGenerator.class);
2) EasyMock:
Import: import org.easymock.EasyMock;
Use: We are going to use EasyMock to fake our object to be returned by our static method:
EasyMock.expect(IdGenerator.generateNewId()).andReturn(42L);
These was two examples on what are used PowerMock and EasyMock, and here I'll try to explain the code and what it does:
mockStatic(IdGenerator.class);
//We mock our IdGenerator class which have the static object
expect(IdGenerator.generateNewId()).andReturn(42L);
//We fake our method return object, when we'll call generateNewId()
//method it will return 42L
//With expecting we "record" our this method and we prepare it to be
//changed (it will return our decided value)
replay(IdGenerator.class);
//We go to perform our methods "registered" with the expect method
//inside the IdGenerator class, in this case with replay we just apply
//the changes of the expect to the method generateNewId()
long actualId = serTestObj.registerService();
//We create our object (which inside have a non static method that
//use generateNewId() static method)
verify(IdGenerator.class);
//We verify that the our faked method have been called
assertEquals(42L,actualId);
//We see if the two values are matching
Pay attention because replay must be used before you create the new object (actualId in this example) that will call the static faked methods.
Also do a lot of attention on what you are importing, for a distraction i was using
PowerMockito.mockStatic(className.class);
//from import org.powermock.api.mockito.PowerMockito;
Instead of
PowerMock.mockStatic(className.class);
//from import org.powermock.api.easymock.PowerMock;
I hope that this answer is clear and complete
By the way here i'll refer you to some useful links:
PowerMock Static Documentation on GitHub
Mvn Repository PowerMock Libraries
See you :D

Mock Runtime.getRuntime()?

Can anyone make any suggestions about how best to use EasyMock to expect a call to Runtime.getRuntime().exec(xxx)?
I could move the call into a method in another class that implements an interface, but would rather not in an ideal world.
interface RuntimeWrapper {
ProcessWrapper execute(String command) throws IOException;
}
interface ProcessWrapper {
int waitFor() throws InterruptedException;
}
I was wondering if anyone had any other suggestions?

Your class shouldn't call Runtime.getRuntime(). it should expect a Runtime to be set as its dependency, and work with it. Then in your test you can easily provide a mock and set it as a dependency.
As a sidenote, I'd suggest watching this lecture on OO Design for testability.
Update: I didn't see the private constructor. You can try using java bytecode instrumentation in order to add another constructor or make the constructor public, but that might turn out to be impossible as well (if there are some restrictions on that class).
So your option is to make a wrapper (as you suggested in the question), and follow the dependency-injection approach.

Bozho above is IMO the Correct Solution. But it is not the only solution. You could use PowerMock or JMockIt.
Using PowerMock:
package playtest;
public class UsesRuntime {
public void run() throws Exception {
Runtime rt = Runtime.getRuntime();
rt.exec("notepad");
}
}
package playtest;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.legacy.PowerMockRunner;
import static org.powermock.api.easymock.PowerMock.*;
import static org.easymock.EasyMock.expect;
#RunWith(PowerMockRunner.class)
#PrepareForTest( { UsesRuntime.class })
public class TestUsesRuntime {
#Test
public void test() throws Exception {
mockStatic(Runtime.class);
Runtime mockedRuntime = createMock(Runtime.class);
expect(Runtime.getRuntime()).andReturn(mockedRuntime);
expect(mockedRuntime.exec("notepad")).andReturn(null);
replay(Runtime.class, mockedRuntime);
UsesRuntime sut = new UsesRuntime();
sut.run();
}
}

Perhaps instead of mocking Runtime.getRuntime().exec() you could "mock" the script/program/etc. it's supposed to be calling.
Instead of passing the real command-line string into exec(), write a test script and execute it instead. You could have the script return hard-coded values you could test against just like a mocked class.

Here is how you would do it with EasyMock 3.0 (and JUnit 4):
import org.junit.*;
import org.easymock.*;
import static org.easymock.EasyMock.*;
public final class EasyMockTest extends EasyMockSupport
{
#Test
public void mockRuntimeExec() throws Exception
{
Runtime r = createNiceMock(Runtime.class);
expect(r.exec("command")).andReturn(null);
replayAll();
// In tested code:
r.exec("command");
verifyAll();
}
}
The only problem with the test above is that the Runtime object needs to be passed to code under test, which prevents it from using Runtime.getRuntime().
With JMockit, on the other hand, the following test can be written, avoiding that problem:
import org.junit.*;
import mockit.*;
public final class JMockitTest
{
#Test
public void mockRuntimeExec() throws Exception
{
final Runtime r = Runtime.getRuntime();
new NonStrictExpectations(r) {{ r.exec("command"); times = 1; }};
// In tested code:
Runtime.getRuntime().exec("command");
}
}