You can also add this to your world so you need only set it once.

class MechanizeWorld < Webrat::MechanizeSession

def mechanize

return @mechanize unless @mechanize.nil?

@mechanize = Mechanize.new

# Get proxy from http_porxy environment var
if ENV['http_proxy'] != nil
proxy = URI.parse(ENV['http_proxy'])
@mechanize.set_proxy(proxy.host, proxy.port)
end

@mechanize

end

end

World do
MechanizeWorld.new
end