Rspec controller test strange error: undefined method `call' for nil:NilClass

Testing RSpec
1

must be doing something dumb…
not sure, but the ‘call’ appears to be on the block.call when the
respond_to block gets executed.

straight forward “channels” resource with a ‘create’ action… only
new thing is just assigning the current_user to the model.

def create
@channel = Channel.new(params[:channel])
@channel.user = @user
respond_to do |format|
if @channel.save
flash[:notice] = ‘Channel was successfully created.’
redirect_to(@channel)
else
flash[:error] = ‘Error saving Channel.’
render :action => “new”
end
end
end

modifying the scaffold spec like this
produces strange

def mock_channel(stubs={})
@mock_channel ||= mock_model(Channel, stubs)
end
def mock_user(stubs={})
@mock_user ||= mock_model(User, stubs)
end
before(:each) do
@mock_user = mock_user
controller.stub(:current_user).and_return @mock_user
end

describe “POST create” do

describe "with valid params" do
  it "assigns a newly created channel as @channel" do
    mock_channel(:save => true)
    @mock_channel.should_receive(:user=).with(@mock_user)
    Channel.stub(:new).with({'these' =>

‘params’}).and_return(mock_channel)
debugger
post :create, :channel => {:these => ‘params’}
assigns[:channel].should equal(mock_channel)
end

it fails on the post :create line …reporting
undefined method `call’ for nil:NilClass
at …/.rvm/gems/ruby-1.8.7-p249/gems/activesupport-2.3.5/lib/
active_support/whiny_nil.rb:52
raise_nil_warning_for klass, method, caller
51 else
52 super
53 end
54 end

another clue perhaps is that if you remove the :save => true stub
option, then it works …but fails at the
if @channel.save line …reporting
Mock “Channel_1002” received unexpected message :save with (no args)

thanks in advance