Play 2.4: How do I disable routes file loading during unit tests?

Background: I am using Play 2.4 (Java) with InjectedRoutesGenerator and a Guice module to configure various dependencies. But during unit tests, the FakeApplication is trying to load all the Controllers from routes file through the injector and some of them are failing due to external dependencies not available in the unit test environment.

How do I disable the default routes file processing during unit tests that extend from play.test.WithApplication? Or how can I replace the default routes with a custom routes file?

I tried to use the play.http.router config option override referenced here, but I get Router not found error with anything I tried. Obviously I am making some mistake, I am not sure where.

I am not quite understanding the link between the my.application.Router and conf/my.application.routes referenced in the config reference. Route files other than routes do not get compiled either.

I am answering my own question here. After spending some more time with Play source code, I figured out the connection between the routes file and the generated Router class. Hope it helps someone else.

Play's route compiler task compiles all files in conf folder ending with .routes as well as the default routes file. Generated class name is always Routes, but the package name depends on the file name. If the file name is routes (the default routes file), compiled class is placed in router package, so the fully qualified class name is router.Routes (which is the default value for play.http.router).

For all other route files, RouteCompiler derives the package name by dropping the .routes from the file name. So for my.test.routes, play.http.router value should be my.test.Routes.

Here is the base class for my tests, with custom router and db configuration elements.

public class MyTestBase extends WithApplication {
    @Override
    protected Application provideApplication() {
        Application application = new GuiceApplicationBuilder()
                .configure("db.default.driver", "org.h2.Driver")
                .configure("db.default.url", "jdbc:h2:mem:play")
                .configure("play.http.router", "my.test.Routes")
                .build();
        return application;
    }
}