Spy doesn't get called using async jasmine and requirejs - angularjs

Question

I have a setup of AngularJS application that uses RequireJS to download and register services on-demand. I also use Jasmine for testing. I am trying to test if a function is called in the callback of a require() call that is executed inside of a module definition. Look at the following file I have and want to test:
define(['app'], function(app) {
app.registerService('myService', function($injector) {
this.someMethod = function() {
require(['some-other-file'], function() {
var someOtherService = $injector.get('someOtherService');
console.log("first");
someOtherService.bla();
});
};
});
});
I want to test that when myService.someMethod() is called, someOtherService.bla() is also called. This is my test file:
define(['some-file', 'some-other-file'], function() {
//....
it('should test if someOtherService.bla() is called', function(done) {
inject(function($rootScope, myService, someOtherService) {
spyOn(someOtherService, 'bla');
myService.someMethod();
$rootScope.$digest();
setTimeout(function() {
console.log("second");
done();
}, 500);
expect(someOtherService.bla).toHaveBeenCalled();
});
});
});
The console output shows that the statements are executed in the right order:
"first"
"second"
But the test fails, because the spy method never gets called. Why is that and how can I fix it? I very much appreciate your help.