PowerMock: Sample usage of expectNew and expectStrictNew...

Depencencies

• 'org.powermock:powermock-api-easymock:1.5.1'
• 'org.powermock:powermock-module-junit4:1.5.1'
• 'org.easymock:easymock:3.1'

PowerMockDemo

public class PowerMockDemo {
 
  public void someMethod(String someArgument){
  
  ClassA a = new ClassA();
  ClassB b = new ClassB();
  ClassC c = new ClassC();

  c.setFirst(a);
  c.setSecond(b);
  c.execute(someArgument);
 }
}

PowerMockDemoTest

Below is the unit test to test the PowerMockDemo.java.

import static org.powermock.api.easymock.PowerMock.*;
import org.easymock.EasyMock;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest(PowerMockDemo.class)
public class PowerMockDemoTest {
 
 private PowerMockDemo toTest;
 
 @Test
 public void testExcuteMethod() throws Exception {
  
  toTest = new PowerMockDemo();
 
  ClassA mockA = createMock(ClassA.class);
  expectNew(ClassA.class).andReturn(mockA);
  
  ClassB mockB = createMock(ClassB.class);
  expectNew(ClassB.class).andReturn(mockB);
  
  ClassC mockC = createStrictMock(ClassC.class);
  expectNew(ClassC.class).andReturn(mockC);
  
  mockC.setFirst(mockA);
  expectLastCall().once();
  
  mockC.setSecond(mockB);
  expectLastCall().once();
  
  mockC.execute(EasyMock.anyObject(String.class));
  expectLastCall().once();
  
  replayAll();
  
  // run the test code
  toTest.someMethod("Hello PowerMock");
  
  verifyAll();
 }
}

In the unit test above we asserted several things when the PowerMockDemo#someMethod(String) is invoked.

PowerMock.createMock() - is used to instantiate a new mock object.

PowerMock.expectNew() - is used to specify that a new a new instance is expected and when it is invoked the specified mock object is returned.

PowerMock.createStrictMock() - is also used to create a new mock object. The only difference is that, when compared to createMock(), the order of method invocations on the mock object is asserted.

References:

• PowerMock
• EasyMock