I am currently in a class for software testing where for our semester project, we have to perform multiple types of testing on it, such as unit testing and integration testing.  For integration testing, the professor said to use mocks and mocking libraries (like EasyMock and Mockito) for our integration testing.  I'm getting fairly confused though.  Integration testing is testing outside classes, modules, services, etc.  Why would mocks and stubs be proper to use in integration testing if you are testing a multiple classes and services?
Does integration testing use mocks?
unit testing;testing;integration tests;mocking