Injector.java

package matera.spi.messaging;

import org.mockito.Mockito;

import java.lang.reflect.Field;

/**

Example to use:
<PRE>
   new Injector<MessageValidator, Message>()
        .injectMock(MessageValidator.class)
        .in(new Message())
        .on("messageValidator");
</PRE>
   
After each test may be you need clean and reset mock object like this:

<PRE>
    @AfterEach
    public void afterEach() {
        Mockito.reset(this.messageValidator);
        Mockito.clearInvocations(this.messageValidator);
     }
</PRE>
 */
public class Injector<C, I> {
    Class<C> inject;
    I in;
    
    public Injector<C, I> injectMock(Class<C> inject) {
        this.inject = inject;
        return this;
    }

    public Injector<C, I> in(I in) {
        this.in = in;
        return this;
    }
    
    public C on(String fieldName) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
        Field field = in.getClass().getDeclaredField(fieldName);
        field.setAccessible(true);
        C mocked = Mockito.mock(inject);
        field.set(in, mocked);
        return mocked;
    }
    
}