How-to: Mock the MessageProvider in tests.

If a class, which is unit tested, have a dependency to the com.alpha.pineapple.i18n.MessageProvider interface, then the Pineapple test utilities contains an EasyMock answer class which can be use to configure a Mock MessageProvider to:

  • log the requested messages.
  • provide a response to a requested message.

To use the EasyMock answer class follow these steps:

  • Setup the mock MessageProvider in the test case.
  • Setup the EasyMock MessageProviderAnswerImpl in the test case.
  • Write your test methods.

Setup the mock MessageProvider in the test case

Create the JUnit test class which should contain the tests which needs access to the test methods.

Define a field in the test class with the message provider:

        
   /**
     * Mock message provider.
     */
    MessageProvider messageProvider;

Create the mock message source in the JUnit setUp() method and inject it into the class under test:

        
    // create mock provider
    messageProvider = EasyMock.createMock( MessageProvider.class );
            
    // inject message provider
    ReflectionTestUtils.setField( classUnderTest, "messageProvider", messageProvider, MessageProvider.class );

Setup the EasyMock MessagePRoviderAnswerImpl in the test case

Define how the mock message source should react during test execution: 

        
    // complete mock provider initialization        
    IAnswer<String> answer = new MessageProviderAnswerImpl(); 
    
    EasyMock.expect( messageProvider.getMessage(
                (String) EasyMock.isA( String.class ), 
                (Object[]) EasyMock.anyObject()));
    EasyMock.expectLastCall().andAnswer(answer).anyTimes();
    
    EasyMock.replay(messageProvider);

Example

public class TestResolveNameToIPAddressCommandTest
{

    /**
     * Command under test.
     */
    Command command;

    /**
     * Chain context.
     */
    Context context;

        /**
         * Mock execution result.
         */
        ExecutionResult executionResult; 
        
    /**
     * Mock message provider.
     */
    MessageProvider messageProvider;
                
    @Before
    public void setUp() throws Exception
    {
        // create command
        command = new TestResolveNameToIPAddressCommand();

        // create context
        context = new ContextBase();
        
        // create mock result
        executionResult = EasyMock.createMock( ExecutionResult.class );   
        
        // create mock provider
        messageProvider = EasyMock.createMock( MessageProvider.class );
                
        // inject message source
        ReflectionTestUtils.setField( command, "messageProvider", messageProvider, MessageProvider.class );
        
        // complete mock source initialization        
        IAnswer<String> answer = new MessageProviderAnswerImpl(); 
        
        EasyMock.expect( messageProvider.getMessage(
                        (String) EasyMock.isA( String.class ), 
                        (Object[]) EasyMock.anyObject()));
        EasyMock.expectLastCall().andAnswer(answer).anyTimes();
        
        EasyMock.replay(messageProvider);        
    }

        // remaining part of the test class goes here...
                
}