Return extension classes with wildcard type arguments

Currently a family of PluginManager#getExtensionClasses(Class<T> extensionType, …) return List<Class<T>>. That, however, makes mocking quite hard:

when(pluginManager.getExtensionClasses(Service.class, pluginId))
    .thenReturn(ImmutableList.of(TestService1.class));
// Won't compile, because List<Class<TestService1>> is not assignable
// to List<Class<Service>>

when(pluginManager.getExtensionClasses(Service.class, pluginId))
    .thenReturn(ImmutableList.of(TestService1.class, TestService2.class)); 
// Won't compile, because List<Class<? extends Service>> is not assignable
// to List<Class<Service>>

when(pluginManager.getExtensionClasses(Service.class, pluginId))
    .thenReturn(ImmutableList.of((Class<Service>) TestService1.class); 
// Won't compile, because Class<TestService1>> cannot be
// cast to Class<Service>.

I suggest returning List<Class<? extends T>> to make the interface more flexible.

Workaround 1

Add a method to perform conversion:

  @SuppressWarnings("unchecked")
  @SafeVarargs
  private static <T> List<Class<T>> extensions(Class<? extends T>... extensions) {
    return Arrays.stream(extensions)
        .map(extensionClass -> (Class<T>) extensionClass)
        .collect(toList());
  }

Workaround 2

(Not really)

thenReturn(ImmutableList.of(
  ((Class<Service>) ((Class<? extends Service>) TestService1.class))
));

[dmitry-timofeev]

Hi, I think I’ll try in the coming week.-- Best wishes,Dmitry Timofeev21.03.2019, 15:23, “Decebal Suiu” [e-mail]:@dmitry-timofeev Can you submit a PR for pf4j_3 branch? Thanks!

—You are receiving this because you were mentioned.Reply to this email directly, view it on GitHub, or mute the thread.

[decebals]

We use the first workaround in the project.

That means that you use PF4J. Good 👍 😄.