Rails 3 tutorial Ch. 10.6 ex 5 rspec failure

In solving exercise 5, I ran into a similar issue as this question. I refactored based on the answer given to that question but am still receiving the failure:

1) UsersController DELETE 'destroy' as an admin user should not self-destruct
     Failure/Error: lambda do
       count should have been changed by 0, but was changed by -1
    # ./spec/controllers/users_controller_spec.rb:354:in `block (4 levels) in <top     (required)>'

My spec:

  it "should destroy the user" do
    lambda do
      delete :destroy, :id => @user
    end.should change(User, :coun开发者_StackOverflowt).by(-1)
  end

  it "should redirect to the users page" do
    delete :destroy, :id => @user
    response.should redirect_to(users_path)
  end

  it "should not self-destruct" do
    lambda do
      delete :destroy, :id => @user.id
    end.should change(User, :count).by(0)
  end

and my controller:

def destroy
  @user = User.find(params[:id])
  if current_user == @user
    flash[:notice] = "You cannot destroy yourself"
  else
    @user.destroy
     flash[:success] = "User destroyed"  
  end
  redirect_to users_path
end

I've checked the behavior in the browser and it works as expected. As always, any help is appreciated. Thanks!

The updated, working code:

describe "as an admin user" do

  before(:each) do
    @admin = Factory(:user, :email => "admin@example.com", :admin => "true")
    test_sign_in(@admin)
  end

  it "should have links to destroy a user" do
    get :index
    response.should have_selector("a", :content => "delete" )
  end

  it "should destroy the user" do
    lambda do
      delete :destroy, :id => @user
    end.should change{ User.count }.by(-1)
  end

  it "should redirect to the users page" do
    delete :destroy, :id => @user
    response.should redirect_to(users_path)
  end

  it "should not be allowed to delete itself" do
    lambda do
      delete :destroy, :id => @admin
    end.should_not change{ User.count }
  end
end

I just realised that I read the wrong one of the three tests you posted (it would be clearer if you only posted the failing test :)

However I'm confused, your "it should not self destruct" test is exactly the same as "it should destroy the user":

it "should destroy the user" do
  lambda do
    delete :destroy, :id => @user
  end.should change(User, :count).by(-1)
end

it "should not self-destruct" do
  lambda do
    delete :destroy, :id => @user.id
  end.should change(User, :count).by(0)
end

You're running the same test both times but expecting different outcomes. I would take a look again at the "it should not self destruct" and see what you mean by that (I'm not sure).

I would guess that what needs to change is whatever is in the `change( xxxx ).by(0). What is it that shouldn't be changing through the test?

This bit me for a long time too. Try changing your syntax from:

should change(User, :count).by(-1)

to:

should change{ User.count }.by(-1)

Or try doing:

This is getting a little away from the book but you could try changing your syntax. The RSpec recommendation for this type of expectation is:

it "should destroy the user" do
  expect{
    delete :destroy, :id => @user
  }.to change{ User.count }.by(-1)
end

Which I actually think is much cleaner and more readable anyway. Could you provide a link to the example as it is in the book?