Rspec with inherited_resources is redirecting instead of rendering on failed update

Question

I am new to both rspec and inherited_resources. I have a simple resource, Contact, that has a name field. The controller has no special functionality.

class ContactsController <  InheritedResources::Base 
  actions :all, :except => [:show]
end

I have written specs for create and index just fine, using mock_model. However, when using mock_model on update, it couldn't find the contact when putting. So, I switched to using real models:

describe "PUT update" do
let(:contact) { Contact.create(:name => "test 1") }

it "edits the contact" do
  contact.name = "#{contact.name}-edited"
end
context "when the contact updates successfully" do
  before do
    contact.stub(:save).and_return(true)
  end
  it "redirects to the Contacts index" do
    put :update, :id => contact.id, :contact => contact
    #assigns[:contact].name = "test 1 - edited"
    response.should redirect_to(:action => "index")
  end
end

context "when the contact fails to save" do
  before do
    contact.stub(:save).and_return(false)
    contact.stub(:update_attributes).and_return(false)
    contact.stub(:errors).and_return(:errors => { :anything => "anything" })
  end
  it "renders the edit template" do
    put :update, :id => contact.id, :contact => contact
    response.should render_template :edit
  end
end
end

I get the following error:

Failures:

  1) ContactsController PUT update when the contact fails to save renders the edit template
   Failure/Error: response.should render_template :edit
   Expected block to return true value.
   # ./spec/controllers/contacts_controller_spec.rb:82:in `block (4 levels) in <top (required)>'

When I inspect the status_code, it's a 302 redirect to /contacts/:id.

What am I doing wrong?