Fail your build for user-defined style rules.

dynamic_method_spec.rb

require 'spec/support/grep_matcher'

describe do
  disallow_presence_of pattern: "send(.*#",
    location: "app/",
    description: "Do not use dynamic method invocations",
    failure: "Please change dynamic method call to something more sane."
end

grep_matcher.rb

# Soon to be open sourced as a gem
module Reverb
  module RSpec
    module GrepMatcher
      module ClassMethods
        def disallow_presence_of(description:nil, pattern:nil, location:nil, failure:nil)
          it(description) do
            results = `grep -rn '#{pattern}' #{location}`
            results.should eq(""), failure
          end
        end
      end
    end
  end
end

RSpec::Core::ExampleGroup.extend(Reverb::RSpec::GrepMatcher::ClassMethods)

<3

You can make these tests faster with https://github.com/ggreer/the_silver_searcher

Or, simply, git grep.