Autowiring of beans generated by EasyMock factory-method?

I have a problem that seems really strange to me. I have the following setup:

An interface:

package com.example;

public interface SomeDependency {
}

A spring component:

package com.example;

@Component
public class SomeClass {
}

A spring test config with a mocked bean generated by EasyMock:

<beans ....>
    <context:component-scan base-package="com.example"/>

    <bean id="someInterfaceMock" class="org.easymock.EasyMock" factory-method="createMock">
        <constructor-arg value="com.example.SomeDependency" />
    </bean> 
</beans>

And a unit test:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("/testconfig.xml")
public class SomeClassTest {

    @Autowired
    SomeClass someClass;

    @Autowired
    SomeDependency someDependency;

    @Test
    public void testSomeClass() throws Exception {
        assertNotNull(someClass);
    }

    @Test
    public void testSomeDependency() throws Exception {
        assertNotNull(someDependency);
    }
}

The project compiles and the tests pass without any problem, i.e. autowiring of both SomeClass (a "real" object) and SomeDependency (a mock object generated by EasyMock) succeed.

However, if I change the implementation of SomeClass to:

@Component
public class SomeClass {

    @Autowired
    SomeDependency someDependency;
}

both tests fail because

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.example.SomeDependency] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

So my questions are:

1. Why does Spring fail