Teja Kantamneni: easymock

Thursday, September 11, 2008

Partial mocking of objects using easymock classextensions

Ocassionally, some of your methods in your classes need to call some other public methods in the same class to get the job done. But when writing unit tests for the calling methods, you want to keep your tests isolated from the calls to other public methods. I encountered such a scenario recently and found that Easymock can help you by mocking some of the methods while keeping the rest of the methods intact.

Let us see an example,
The BlogSearchService has two public methods, first method filterBlogsByAuthor takes an author name and a list of blogs and returns all the blogs written by that particular order author.
The other business method searchBlogs will take a search paramter and the author, it will get all the blogs by the search parameter using a custom logic and do some other house keeping tasks like sorting them by published date and number of comments and then filter the methods by author.


package com.teja.blogs;

import java.util.Collections;
import java.util.List;

/**
*
* @author Teja
*/
public class BlogSearchService {

      public List<Blog> searchBlogs(String searchString, String author){

              //do some custom logic here on these blogs like sorting them by posted date.
              return filterBlogsByAuthor(author, Collections.EMPTY_LIST);
      }

      public List<Blog> filterBlogsByAuthor(String author, List<Blog> blogs){
              return Collections.EMPTY_LIST;
      }

}

When writing the test cases for the second method, I don't want to test the other public method filterByAuthor as
(i)it has already been tested by other test cases,
(ii)I want to keep my test cases more unit.

So in my test case where I am testing my searchBlogs, I am creating the mock service class which has mock methods only for filterBlogsByAuthor, but the actual mehtod(searchBlogs) which is about to be tested is not.
As usual you can do expectations on the mock class, replay and verify as if it is some other external resource being mocked.

To create a partial mock class of the service, the extra parameter you need to pass is the name of the method to be mocked and the parameter types it accepts (coz, it need to know which version of the method you want to mock if you have overloaded methods)

Here is our test class:


package com.teja.blogs;

import java.util.Collections;
import java.util.List;
import org.junit.Test;
import org.easymock.classextension.EasyMock;

/**
*
* @author Teja
*/
public class BlogSearchServiceTest {

        @Test
        public void testSearchBlogs() throws NoSuchMethodException {
                String author = "Teja";
                BlogSearchService blogSearchService =EasyMock.createMock(BlogSearchService.class,
                BlogSearchService.class.getMethod("filterBlogsByAuthor", new Class[]{String.class, List.class}));
                EasyMock.expect(blogSearchService.filterBlogsByAuthor(author, Collections.EMPTY_LIST)).andReturn(Collections.EMPTY_LIST);
                EasyMock.replay(blogSearchService);
                blogSearchService.searchBlogs("easymock", author);
                EasyMock.verify(blogSearchService);
        }

}

Saturday, August 23, 2008

Testing Spring applications with jUnit 4 and Easy Mock

Unit tests help us make sure that the unit chunks of code being developed are correct. Unit test helps find bugs in the early stages of software development.

Java unit testing frameworks like jUnit, TestNG with some other pretty frameworks like easy mock and easy mock class extensions help us test individual classes with mocking out the external dependent classes/resources and make the tests more "unit".

Spring out of the box supports unit testing with jUnit and TestNG. Spring provides seperate set of classes help you unit test your spring classes.

Spring 2.5 in its org.springframework.test.context package has a set of classes to have better unit testing using jUnit4.

I am about to show an example of testing a service called BlogSearchService. The service simply calls a method in the blogDAO which searches the blogs based on the keyword and return a list of blogs. So here my service class is simple, it calls the DAO. So in my test I just have to make sure that it makes a DAO call and the result is then returned to the client.

Lets see the code for BlogSearchService and BlogSearchServiceImpl,

BlogSearchService.java

package com.teja.tests;
import java.util.List;
/**
 *
 * @author Teja Kantamneni
 */

public interface BlogSearchService {
    public List<Blog> searchBlogByKeyWord(String keyword);
}

BlogSearchServiceImpl.java

 
package com.teja.tests;

import java.util.List;

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

/**

 *

 * @author Teja Kantamneni

 */

public class BlogSearchServiceImpl implements BlogSearchService {

    @Autowired

    BlogDAO blogDAO;

    public List<Blog> searchBlogByKeyWord(String keyword){

        return blogDAO.searchByKeyword(keyword);

    }

    public void setBlogDAO(BlogDAO blogDAO) {

        this.blogDAO = blogDAO;

    }

}

Here is the test case for BlogSearchService,
In the test case, the ContextConfiguration helps in specifying the config file to load. In the @Before (setup method for the test case) I am creating the instance of BlogSearchServiceImpl (but instead you can autowire it). Then I am creating the mock object of blogDAO and setting it to the BlogSearchService. In the actual test method, I expect that the searchBlogByKeyWord on the blogDAO and I am expecting it retuning no posts. You can do any asserts here depending on the actual business.

SpringJUnit4ClassRunner is a custom extension of JUnit4ClassRunner which provides functionality of the Spring TestContext Framework to standard JUnit 4.4+ tests by means of the TestContextManager and associated support classes and annotations.

 
package com.teja.tests;

import java.util.Collections;

import org.junit.Before;

import org.junit.Test;

import org.junit.runner.RunWith;

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

import org.springframework.test.context.ContextConfiguration;

import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import static org.easymock.EasyMock.*;

/**

 *

 * @author Teja Kantamneni

 */

@RunWith(SpringJUnit4ClassRunner.class)

@ContextConfiguration(locations = {"classpath:beans.xml"})

public class BlogSearchServiceTest {

    @Autowired

    BlogSearchServiceImpl blogSearchService;

    BlogDAO blogDAO;

    @Before

    public void setUp(){

        blogSearchService = new BlogSearchServiceImpl();

        blogDAO = createMock(BlogDAO.class);

        blogSearchService.setBlogDAO(blogDAO);

    }

    @Test

    public void testSearchBlogByKeyword(){

        String keyword = "spring";

        expect(blogDAO.searchByKeyword(keyword)).andReturn(Collections.EMPTY_LIST);

        replay(blogDAO);

        blogSearchService.searchBlogByKeyWord(keyword);

        verify(blogDAO);

    }

}

It's so simple and sweet testing spring classes with jUnit and easymock. Isn't it?