sinon- assert args on function with stubs

How can I assert on the args of this function with stubs?

  templatesResource.one = function(arg) {
    if (arg == 'apple'){
      get: sinon.stub().returns getTemplatesDeferred.promise
    } else {
      get: sinon.stub().returns getTemplatesDeferred.promise
   }
  }

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expect(templatesResource.one).to.have.been.calledWith(123)