Jasmine: Mocking inner method of singleton

How would I mock the call to a method of a singleton, like:

Foo.get().getBar();

It seems straightforward to mock Foo.getBar(); with

jasmine.createSpyObj(Foo, ['get']);
Foo.get.and.returnValue();

But I've been noodling with dependency injection and can't quite get it to work just right. FWIW: getBar returns a promise, so I'm really trying to mock Foo.get().getBar().then() which I imagine must be something like

Foo.get.getBar.and.callFake(() => { return deferred.promise; });