Mocking static methods with Powermockito

Question

I am trying to mock static method with PowerMockito. I have referred to various stackoverflow answers such as this:Mocking static methods with PowerMock and Mockito

But I am getting : org.mockito.exceptions.misusing.InvalidUseOfMatchersException: Misplaced argument matcher detected here exception. I have spent hours debugging my code and google searching but to no avail. What am I missing here?

* Note: I am running it as a testng test. *

I have added comments in my code that may help you understand what I am trying to do.

The full stack trace is:

 org.mockito.exceptions.misusing.InvalidUseOfMatchersException: 
 Misplaced argument matcher detected here:

 at MyClassTest.testMethod1(MyClassTest.java:24)`

 You cannot use argument matchers outside of verification or stubbing.
 Examples of correct usage of argument matchers: 
    when(mock.get(anyInt())).thenReturn(null);
    doThrow(new RuntimeException()).when(mock).someVoidMethod(anyObject());
    verify(mock).someMethod(contains("foo")) `

 Also, this error might show up because you use argument matchers with methods that cannot be mocked.
 Following methods *cannot* be stubbed/verified: final/private/equals()/hashCode(). 
 Mocking methods declared on non-public parent classes is not supported.`

at MyClassTest.testMethod1(MyClassTest.java:24)
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.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:84)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:714)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:901)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1231)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:127)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:111)
at org.testng.TestRunner.privateRun(TestRunner.java:767)
at org.testng.TestRunner.run(TestRunner.java:617)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:348)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:343)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:305)
at org.testng.SuiteRunner.run(SuiteRunner.java:254)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1224)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1149)
at org.testng.TestNG.run(TestNG.java:1057)
at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:132)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:230)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:76)

`

Below is my code:

Test Class

import static org.mockito.Matchers.anyString;
import org.junit.runner.RunWith;
import org.mockito.BDDMockito;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import org.testng.annotations.Test;

@Test
@RunWith(PowerMockRunner.class)
@PrepareForTest(AnotherClass.class)
public class MyClassTest {

    MyClass myClass;

    @Test
    public void testMethod1() {

        /*
         * Mock static methods
         */
        PowerMockito.mockStatic(AnotherClass.class);
        BDDMockito.given(AnotherClass.yetAnotherMethod(anyString())).willReturn(Mockito.mock(String.class));

        // call the method of system under test
        myClass.method1();

        // verify
        PowerMockito.verifyStatic();
    }

}

System Under Test:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

public class MyClass {

    public String method1() {
        String result = AnotherClass.yetAnotherMethod("Pramithas");
        return result;
    }
}

AnotherClass.java:

import org.springframework.stereotype.Service;

public class AnotherClass {

    public static String yetAnotherMethod(String s) {
        return s;
    }
}

Answer 1

I got your example working with some changes:

@RunWith(PowerMockRunner.class)
@PrepareForTest({ AnotherClass.class })
public class MyClassTest {

@Before
public void setUp() {
  myClass = new MyClass();
}

@Test
public void testMethod1() {

/*
 * Mock static methods
 */
PowerMockito.mockStatic(AnotherClass.class);
BDDMockito.given(AnotherClass.yetAnotherMethod(Mockito.anyString())).willReturn("Hello");

// call the method of system under test
String a = myClass.method1();

// verify
PowerMockito.verifyStatic();
}

I added AnotherClass to PrepareForTest too and I force AnotherClass mock to return a String value because Mockito can't mock final classes and I can check that myClass behave as expected. Here is my Mockito and Powermock dependencies:

<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-core</artifactId>
    <version>2.7.5</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-module-junit4</artifactId>
    <version>1.7.0RC2</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-api-mockito2</artifactId>
    <version>1.7.0RC2</version>
    <scope>test</scope>
</dependency>

Answer 2

1. You haven't created new object for MyClass
2. Do not try to mock primitive types or final classes

3. Removed @Test annotation

   import org.junit.Test;
   import org.junit.runner.RunWith;
   import static org.mockito.Matchers.anyString;
   import org.mockito.BDDMockito;
   import org.powermock.api.mockito.PowerMockito;
   import org.powermock.core.classloader.annotations.PrepareForTest;
   import org.powermock.modules.junit4.PowerMockRunner;
   
   @RunWith(PowerMockRunner.class)
   @PrepareForTest(AnotherClass.class)
   public class MyClassTest {`
   
     MyClass myClass = new MyClass();
   
    @Test
    public void testMethod1() {
   
      /*
       * Mock static methods
       */
      PowerMockito.mockStatic(AnotherClass.class);
   BDDMockito.given(AnotherClass.yetAnotherMethod(anyString())).willReturn("any String");    
   
      // call the method of system under test
      myClass.method1();
   
      // verify
      PowerMockito.verifyStatic();
    }
   }
   

This is verified. It should work.