shoulda_been_a_spec.rb

#!/usr/bin/env ruby

REGXS = {
    /context/ => "describe",
    /assert_equal\(?\s*([^,]+), (.*)\s*\)?$/ => "\\2.should == \\1",
    /setup do/ => "before( :each ) do",
    /should([^_])/ => "it\\1",
    /require File.dirname.*$/ => "require \"spec_helper\"",
    /class (.*)Test < [^:]*::TestCase/ => "describe \\1 do"
  }

infile  = ARGV.first
outfile = infile.gsub( /_test.rb/, "_spec.rb" ).gsub( %r{test/unit/helpers}, "spec/helpers" )

File.open( outfile, "w" ) do |f|
  ARGF.each do |line|
    out = REGXS.inject( line ) do |result, subs|
      regx, substitution = subs
      result = result.gsub( regx, substitution )
    end
    f.puts out
  end
end

system "mate #{outfile}"
system "git rm #{infile} && git add #{outfile}"
system "bundle exec spec #{outfile}"

puts "\n\nSUCCESS!  Now do this:"
puts "rake && git commit -m \"Converted #{File.basename infile} from should to rspec in #{File.basename outfile}\""