```ruby
require 'selenium/webdriver'

class Selenium::WebDriver::Firefox::Profile
  def enable_firebug(version = "1.6.2")
    add_extension(File.expand_path("../firebug-#{version}.xpi", __FILE__))

    # Prevent "Welcome!" tab
    self["extensions.firebug.currentVersion"] = "999"

    # Enable for all sites.
    self["extensions.firebug.allPagesActivation"] = "on"

    # Enable all features.
    ['console', 'net', 'script'].each do |feature|
      self["extensions.firebug.#{feature}.enableSites"] = true
    end

    # Closed by default.
    self["extensions.firebug.previousPlacement"] = 3
  end
end

Capybara.register_driver :selenium_with_firebug do |app|
  profile = Selenium::WebDriver::Firefox::Profile.new
  profile.enable_firebug
  Capybara::Driver::Selenium.new(app, :browser => :firefox, :profile => profile)
end

if defined?(Cucumber)
  Before '@firebug' do
    Capybara.current_driver = :selenium_with_firebug
  end

  Then /^stop and let me debug$/ do
    require 'ruby-debug'
    debugger
  end
end
```

Check a different constant for Cucumber.
user
```ruby
require 'selenium/webdriver'

class Selenium::WebDriver::Firefox::Profile
  def enable_firebug(version = "1.6.2")
    add_extension(File.expand_path("../firebug-#{version}.xpi", __FILE__))

    # Prevent "Welcome!" tab
    self["extensions.firebug.currentVersion"] = "999"

    # Enable for all sites.
    self["extensions.firebug.allPagesActivation"] = "on"

    # Enable all features.
    ['console', 'net', 'script'].each do |feature|
      self["extensions.firebug.#{feature}.enableSites"] = true
    end

    # Closed by default.
    self["extensions.firebug.previousPlacement"] = 3
  end
end

Capybara.register_driver :selenium_with_firebug do |app|
  profile = Selenium::WebDriver::Firefox::Profile.new
  profile.enable_firebug
  Capybara::Driver::Selenium.new(app, :browser => :firefox, :profile => profile)
end

if defined?(Cucumber::RbSupport)
  Before '@firebug' do
    Capybara.current_driver = :selenium_with_firebug
  end

  Then /^stop and let me debug$/ do
    require 'ruby-debug'
    debugger
  end
end
```
assistant