Rakefile

#############################################################################
#
# Helper functions
#
#############################################################################

def name
  @name ||= Dir['*.gemspec'].first.split('.').first
end

def version
  line = File.read("lib/#{name}.rb")[/^\s*VERSION\s*=\s*.*/]
  line.match(/.*VERSION\s*=\s*['"](.*)['"]/)[1]
end

def date
  Date.today.to_s
end

def gemspec_file
  "#{name}.gemspec"
end

def gem_file
  "#{name}-#{version}.gem"
end

def replace_header(head, header_name)
  head.sub!(/(\.#{header_name}\s*= ').*'/) { "#{$1}#{send(header_name)}'"}
end

#############################################################################
#
# Standard tasks
#
#############################################################################

require 'rspec'
require 'rspec/core/rake_task'

desc "Run all specs"
task RSpec::Core::RakeTask.new('spec')

task :default => "spec"

desc "Open an irb session preloaded with this library"
task :console do
  sh "irb -rubygems -r ./lib/#{name}.rb"
end

#############################################################################
#
# Custom tasks (add your own tasks here)
#
#############################################################################


#############################################################################
#
# Packaging tasks
#
#############################################################################

desc "Create tag v#{version} and build and push #{gem_file} to Rubygems"
task :release => :build do
  unless `git branch` =~ /^\* master$/
    puts "You must be on the master branch to release!"
    exit!
  end
  sh "git commit --allow-empty -a -m 'Release #{version}'"
  sh "git tag v#{version}"
  sh "git push origin master"
  sh "git push origin v#{version}"
  sh "gem push pkg/#{name}-#{version}.gem"
end

desc "Build #{gem_file} into the pkg directory"
task :build => :gemspec do
  sh "mkdir -p pkg"
  sh "gem build #{gemspec_file}"
  sh "mv #{gem_file} pkg"
end

desc "Generate #{gemspec_file}"
task :gemspec => :validate do
  # read spec file and split out manifest section
  spec = File.read(gemspec_file)
  head, manifest, tail = spec.split("  # = MANIFEST =\n")

  # replace name version and date
  replace_header(head, :name)
  replace_header(head, :version)
  replace_header(head, :date)

  # determine file list from git ls-files
  files = `git ls-files`.
    split("\n").
    sort.
    reject { |file| file =~ /^\./ }.
    reject { |file| file =~ /^(rdoc|pkg)/ }.
    map { |file| "    #{file}" }.
    join("\n")

  # piece file back together and write
  manifest = "  s.files = %w[\n#{files}\n  ]\n"
  spec = [head, manifest, tail].join("  # = MANIFEST =\n")
  File.open(gemspec_file, 'w') { |io| io.write(spec) }
  puts "Updated #{gemspec_file}"
end

desc "Validate #{gemspec_file}"
task :validate do
  libfiles = Dir['lib/*'] - ["lib/#{name}.rb", "lib/#{name}"]
  unless libfiles.empty?
    puts "Directory `lib` should only contain a `#{name}.rb` file and `#{name}` dir."
    exit!
  end
  unless Dir['VERSION*'].empty?
    puts "A `VERSION` file at root level violates Gem best practices."
    exit!
  end
end