public class ModelMapperReMappingTest {

    interface Configurable {

        void configure();

    }

    static class B1 {

        String prop;

        public String getProp() {
            return prop;
        }

        public void setProp(String prop) {
            this.prop = prop;
        }
    }

    static class A1 {

        private B1 b;

        public B1 getB() {
            return b;
        }

        public void setB(B1 b) {
            this.b = b;
        }

    }

    static class B2 implements Configurable {

        String prop;

        @Override
        public void configure() {
            System.out.println("Configuring");
        }

        public String getProp() {
            return prop;
        }

        public void setProp(String prop) {
            this.prop = prop;
        }
    }

    static class A2 {

        private B2 b;

        public B2 getB() {
            return b;
        }

        public void setB(B2 b) {
            this.b = b;
        }
    }

    class ConfigurableEntityProvider implements Provider<Object> {
        @Override
        public Object get(ProvisionRequest<Object> request) {
            if (Configurable.class.isAssignableFrom(request.getRequestedType())) {
                try {
                    Configurable entity = (Configurable) request.getRequestedType().newInstance();
                    entity.configure();
                    return entity;
                } catch (InstantiationException e) {
                    return null;
                } catch (IllegalAccessException e) {
                    return null;
                }
            } else {
                return null;
            }
        }
    }

    @Test
    public void testWithoutMapping() {
        ModelMapper modelMapper = new ModelMapper();
        modelMapper.getConfiguration().setProvider(new ConfigurableEntityProvider());
        A1 aSource = new A1();
        B1 bSource = new B1();
        bSource.setProp("value");
        aSource.setB(bSource);
        A2 target = modelMapper.map(aSource, A2.class);
        B2 bTarget = target.getB();
        Assert.assertEquals("value", target.getB().getProp());
        bSource.setProp("value2");
        modelMapper.map(aSource, target);
        Assert.assertEquals("value2", target.getB().getProp());
        Assert.assertEquals(System.identityHashCode(bTarget), System.identityHashCode(target.getB()));
    }

    @Test
    public void testWithMapping() {
        ModelMapper modelMapper = new ModelMapper();
        modelMapper.addMappings(new PropertyMap<A1, A2>() {
            @Override
            protected void configure() {
                map(source.getB()).setB(null);
            }
        });
        modelMapper.getConfiguration().setProvider(new ConfigurableEntityProvider());
        A1 aSource = new A1();
        B1 bSource = new B1();
        bSource.setProp("value");
        aSource.setB(bSource);
        A2 target = modelMapper.map(aSource, A2.class);
        B2 bTarget = target.getB();
        Assert.assertEquals("value", target.getB().getProp());
        bSource.setProp("value2");
        modelMapper.map(aSource, target);
        Assert.assertEquals("value2", target.getB().getProp());
        Assert.assertEquals(System.identityHashCode(bTarget), System.identityHashCode(target.getB()));
    }

}