RSpec - Object References Itself

Just came across this problem when using RSpec in one the Rails project that I am working on: object references itself.

Object references itself

The project is basically a REST web service which return a project information in JSON format.

In the template file, there is

r.element :project, @project do |project|
    r.element :type
    r.element :manager
end

Which is basically the details of the project including the manager of the project. The manager, is an object, not just a string. Rails is smart enough to map the manager structure into JSON …

As you would have expected the spec files,

let(:manager) { mock(Manager, first_name: "John", last_name: "Doe") }

let(:project) do
    project = Project.from_attributes(type: 'business')
    project.stub!(:manager).and_return(manager);
end

context 'project' do
    subject { custom_render(project) }
    it { subject.should include('manager') }
end

When the test is run, it failed with Object references itself

The cause

It took a while to figure out what was the problem. Turned out that’s because the rspec mock potentially have several methods or attributes that reference itself.

mock(Manager, first_name: "John", last_name: "Doe")

When the above line is executed, it practically creates all the bells and whistle that the mock object has and put all of that onto :manager

r.element :manager

The solution

So the solution was to make sure that we only want to put certain attributes into the view files. Thus the code was updated to

r.element :project, @project do |project|
    r.element :type
    r.element :manager do |manager|
        r.element :type, manager.type
        r.element :name, manager.name
    end
end

and things were working fine again. Both the test and the actual REST web service.

Gotcha

If you notice, the above code potentially has one flaw, what if a project doesn’t have a manager. The attempt to get the manager’s name would crash the web service. Thus it would be good to validate that condition before hand.