How to get bound Instance with Generic via Application.injector() in play2.5

Question

I cannot get access to a guice-bound instance in Play2 tests via the application interface.

Using Play2.5, assume an application using Guice for DI with a Guice module having:

@Singleton
@Provides
protected MyThing<String, Foo, Bar> createMyThing() {
}

In the junit Integration test using WithApplication I do this, using standard play2 classes:

public class ApplicationTest extends WithApplication {

    private Application playApp;

    @Override
    protected Application provideApplication() {
        playApp = new GuiceApplicationBuilder().build();
    }

    @Test
    public void testInject() {
        playApp.injector().instanceOf(new BindingKey<>(MyThing.class));
    }
}

This fails with

No implementation for MyThing was bound

Even though in the debugger, I see the Guice injector has a binding:

MyThing<String, Foo, Bar> -> instance

Now while there are solutions for Guice itself , I cannot seem to directly access those, and the Play DI abstraction does not seem to offer the ability to specify generics.

Answer 1

This hack seems to work to get the Guice Injector, by asking the play injector wrapper to return a bound Guice injector:

play.inject.Injector playInjector = playApp.injector();
com.google.inject.Injector guiceInjector = playInjector.instanceOf(com.google.inject.Injector.class);