Cache Guice Injector with TestNG (another way)

CachedModuleFactory.java

/**
 * @author Andrei Varabyeu
 */
public abstract class CachedModuleFactory implements IModuleFactory {

    /* delegate creating and holding of parent injector to subclass */
    abstract protected Injector getParentInjector();

    abstract protected Module createTestModule(ITestContext context, Class<?> testClass);


    @Override
    final public Module createModule(ITestContext context, Class<?> testClass) {
        Module childModule = createTestModule(context, testClass);
        if (testClass.isAnnotationPresent(UseParentInjector.class)) {
            context.addInjector(Collections.singletonList(childModule),
                    getParentInjector().createChildInjector(childModule));
        }
        return childModule;
    }
}

ModuleFactory.java

    public static class ModuleFactory extends CachedModuleFactory {

        /* Singleton with double-checked locking and lazy initialization using Guava */
        private static final Supplier<Injector> PARENT_INJECTOR = Suppliers.memoize(new Supplier<Injector>() {
            @Override
            public Injector get() {
                //create your parent injector here
                return null;
            }
        });

        @Override
        protected Injector getParentInjector() {
            return PARENT_INJECTOR.get();
        }

        @Override
        protected Module createTestModule(ITestContext context, Class<?> testClass) {
            return new ChildModule();
        }


    }

UseParentInjector.java

/**
 * @author Andrei Varabyeu
 */
@Retention(RUNTIME)
@Target({ElementType.TYPE})
public @interface UseParentInjector {
}