conundrum.js

var Conundrum = {
  doIt: function() {return "did it"; },
  doItCopy: function() {return this.doIt(); }
};

conundrum_spec.js

describe('conundrum',function(){
  describe("faking actual method", function() {
    beforeEach(function() {
      spyOn(Conundrum, "doIt").andReturn("fake");
    });
    
    it("fakes both calls", function() {
      expect(Conundrum.doIt()).toEqual("fake");
      expect(Conundrum.doItCopy()).toEqual("fake");
    });
  });
  
  describe("faking the reference", function() {
    beforeEach(function() {
      spyOn(Conundrum, "doItCopy").andReturn("fake");
    });
    
    it("only fakes the call to the reference", function() {
      expect(Conundrum.doIt()).toEqual("did it");
      expect(Conundrum.doItCopy()).toEqual("fake");
    });
  });
});