Add some tests for setting group preferences.
user
```ruby
require "spec_helper"

describe "Group prefs" do

  def get_field(name)
    find_field(I18n.t("formtastic.labels.group_pref.#{name}"))
  end

  context "as a group member" do
    include_context "signed in as a group member"

    describe "editing the group preferences" do
      it "should refuse" do
        visit edit_group_prefs_path(current_group)
        page.should have_content("You are not authorised to access that page.")
      end
    end
  end

  context "as a group committee member" do
    include_context "signed in as a committee member"

    describe "editing the group preferences" do
      it "should be permitted" do
        visit edit_group_prefs_path(current_group)
        page.should have_content("Edit Preferences")
      end

      describe "membership notifications" do
        let(:field) { get_field("notify_membership_requests") }

        before do
          visit edit_group_prefs_path(current_group)
        end

        it "should default to on" do
          field.should be_checked
        end

        it "should let you turn them off" do
          field.set false
          click_on "Save"
          page.should have_content(I18n.t(".group.prefs.update.success"))
          current_group.reload
          current_group.prefs.notify_membership_requests.should be_false
        end
      end

      it "should let you pick a committee member as membership secretary"
      it "should let you deselect the membership secretary"
      it "should warn about blank emails"
    end
  end

  context "as a site admin" do
    include_context "signed in as admin"

    describe "editing any group preferences she wants to" do
      let(:group) { FactoryGirl.create(:quahogcc) }
      it "should be permitted" do
        visit edit_group_prefs_path(group)
        page.should have_content("Edit Preferences")
      end
    end
  end
end```
assistant