EasyMock is a mock object framework for Java that makes mocking objects easier for unit testing by allowing developers to replace real objects with mock objects to isolate the object being tested and test more code paths such as exceptions. It provides features for stubbing mock methods to return values or throw exceptions, checking method invocations, and verifying expectations after code under test has been called in replay mode. Main mock frameworks for Java include EasyMock, JMockit, Mockito, and JMock.

1. EasyMock
Mock object framework for java
development
By Franck Benault
Created 16/11/2014
Last updated 11/11/2014

2. EasyMock plan

3. Unit test in java
● Main framework : Junit and TestNG
● Database management (fill or check content)
– DbUnit
– DbSetup
● Mock object frameworks
– EasyMock
– Mockito

4. Goal of EasyMock
● On the web site of EasyMock (www.easymock.org)
– Great (unit) testing includes isolation
– Isolation involves mock objects
– EasyMock makes mocking easier

5. What is a mock

6. Mock objects
● Unit tests are white box tests
– The developers is allowed to look at the code
● Mock objects replaces the objects linked to the object we
want to test
● It becomes possible to test more path (exceptions, errors)
● We have to change a little the implementation to make the
mocking easier

7. Mock objects
● Unit tests are white box tests
– The developers is allowed to look at the code
● Mock objects replaces the objects linked to the object we
want to test
● It becomes possible to test more path (exceptions, errors)
● We have to change a little the implementation to make the
mocking easier

8. Features of Mock frameworks
● Main features
– Value returning for a stubbed method
– Exception throwing for a stubbed method
– Invocation check method
– Method arguments check
– Invocation order for one mock check
● Advance features
– Stubbing of equals() and hashCode() methods
– ...

9. Features of Mock frameworks
● Main features
– Value returning for a stubbed method
– Exception throwing for a stubbed method
– Invocation check method
– Method arguments check
– Invocation order for one mock check
● Advance features
– Stubbing of equals() and hashCode() methods
– ...

10. Main mock frameworks (in java)
● Open projects well know
– EasyMock
– Jmockit
– Mockito
– Jmock

11. EasyMock live cycle of mock
objects
● Create a mock
● Set up your expectation
● Set the mock to replay mode
– Call your code under test
● Verify that your expectation have been set

12. EasyMock create mock (strict of
nice)
● Create a mock
– CreateNiceMock()
● Unexpected returns an empty value (0 or null)
– CreateMock()
● The order of the call is not checked
– CreateStrictMock()
● The order of the call is checked

13. EasyMock expection/replay/verify
EntityManager emMock =
EasyMock.createNiceMock(EntityManager.class);
EntityTransaction entityTransactionMock =
EasyMock.createNiceMock(EntityTransaction.class);
EasyMock.expect(emMock.getTransaction()).andReturn(entityT
ransactionMock).times(2);
EasyMock.replay(entityTransactionMock);
EasyMock.verify(entityTransactionMock);

14. EasyMock How to inject the mock
StudentManager StudentQuery

15. EasyMock How to inject the mock
@RunWith(EasyMockRunner.class)
public class StudentManagerMockTest {
@TestSubject //where to inject mocks
private static StudentManager studentManager;
@Mock(type = MockType.NICE) //mock to inject
private StudentQuery studentQueryMock =
EasyMock.createNiceMock(StudentQuery.class);
.../...