controller.rb

  def update
    @rank = Rank.find(params[:id])
    if @rank.update_attributes(params[:rank])
      flash[:notice] = "#{@rank.name} has been updated."
      redirect_to admin_ranks_path
    else
      flash[:notice] = "#{@rank.name} has not been updated."
      render :action => "edit"
    end
  end

download url

Clone the repository using:

git clone git://github.com/Radar/rboard.git

All the code is there, I promise you.
 

error.rb

ActionController::RenderError in 'Admin::RanksController shouldn't be able to update a rank with invalid attributes'
You called render with invalid options : {:action=>"edit", :layout=>false}, nil
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/base.rb:843:in `render_with_no_layout'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/layout.rb:251:in `render_without_benchmark'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/benchmarking.rb:51:in `render'
/Library/Ruby/Gems/1.8/gems/activesupport-2.1.0/lib/active_support/core_ext/benchmark.rb:8:in `realtime'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/benchmarking.rb:51:in `render'
/Users/ryanbigg/Sites/rboard/app/controllers/admin/ranks_controller.rb:34:in `update'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/base.rb:1162:in `send'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/base.rb:1162:in `perform_action_without_filters'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/filters.rb:580:in `call_filters'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/filters.rb:573:in `perform_action_without_benchmark'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/rescue.rb:201:in `perform_action_without_caching'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/caching/sql_cache.rb:13:in `perform_action'
/Library/Ruby/Gems/1.8/gems/activerecord-2.1.0/lib/active_record/connection_adapters/abstract/query_cache.rb:33:in `cache'
/Library/Ruby/Gems/1.8/gems/activerecord-2.1.0/lib/active_record/query_cache.rb:8:in `cache'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/caching/sql_cache.rb:12:in `perform_action'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/base.rb:529:in `send'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/base.rb:529:in `process_without_filters'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/filters.rb:569:in `process_without_session_management_support'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/session_management.rb:130:in `process_without_test'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/test_process.rb:16:in `process'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/test_process.rb:394:in `process'
/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/test_process.rb:365:in `put'
./spec/controllers/admin_ranks_controller_spec.rb:70:

spec example.rb

  it "shouldn't be able to update a rank with invalid attributes" do
    Rank.should_receive(:find).and_return(@rank)
    @rank.should_receive(:name).and_return("Slave")
    @rank.should_receive(:update_attributes).and_return(false)
    put 'update', { :id => ranks(:god).id, :rank  => { :name => "" } }
    response.should render_template("edit")
  end