Bootstrap gem creation for rails application

rails-gem-builder.rb

# The purpose is to create a Gem that has a dummy rails application and uses RSpec as the test framework.

# Check whether gem name is given.
if ARGV.length != 1
  puts "ERROR: We need exactly one parameter. The name of a gem. Eg. MyGem"
  exit;
end

# Initializing dependencies and utilities
require 'active_support/inflector'
require 'open3'
def write_line_under(file_name, regex, string)
  open(file_name, 'r+') do |f|
    while (current_line = f.gets)
      break if regex.match(current_line)
    end

    pos = f.pos
    rest = f.read
    f.seek pos
    f.write string
    f.write rest
  end
end

def run_shell_command(shell_command_in_string)
  puts "$ #{shell_command_in_string}"
  Open3.popen3(shell_command_in_string) do |stdout, stderr, status, thread|
    while line=stderr.gets do
      puts(line)
    end
  end
end

def replace_text(file_name, regex, string)
  file_contents = File.open(file_name).read
  file_contents.gsub!(regex, string)

  File.open(file_name, 'w+') do |f|
    f.write(file_contents)
  end
end

## Script Starts HERE

# Check provided gem name against convention
gem_name = ARGV[0]
if /[A-Z]/.match(gem_name)
  puts "ERROR: Gem Name should not contain uppercase letter. Please refer to http://guides.rubygems.org/name-your-gem/ for Gems naming convention"
  exit;
end

# Create rails plugin gem
#   -T : Ignore tests
#   --dummy-path : set path to create dummy rails application to spec/dummy. Prepare to set up RSpec later
run_shell_command("rails plugin new #{gem_name} -T --dummy-path=spec/dummy")

# Change directory into gem directory
Dir.chdir gem_name

# Add rspec-rails to gemspec file
puts "INFO: Add rspec-rails to gemspec file"
write_line_under("#{gem_name.underscore}.gemspec", /s.add_development_dependency/, "  s.add_development_dependency \"rspec-rails\"\n")

# Fix gemspec details
puts "INFO: Setting gemspec details to default values"
replace_text("#{gem_name.underscore}.gemspec", /s.authors.*=.*/, "s.authors     = [\"SP Digital\"]")
replace_text("#{gem_name.underscore}.gemspec", /s.email.*=.*/, "s.email       = [\"[email protected]\"]")
replace_text("#{gem_name.underscore}.gemspec", /s.homepage.*=.*/, "s.homepage    = \"https://code.in.spdigital.io\"")
replace_text("#{gem_name.underscore}.gemspec", /s.summary.*=.*/, "s.summary     = \"This is a new Gem for rails!\"")
replace_text("#{gem_name.underscore}.gemspec", /s.summary.*=.*/, "s.summary     = \"This is a new utilities Gem for rails!\"")
replace_text("#{gem_name.underscore}.gemspec", /s.description.*=.*/, "s.description = \"This is a new utilities Gem for rails!\"")

# Install dependencies
run_shell_command("bundle install")

# Set up RSpec
Dir.chdir "spec/dummy"
run_shell_command("ln -s ../../spec")
run_shell_command("rails generate rspec:install")
run_shell_command("cd -")
replace_text("spec/rails_helper.rb", /File\.expand_path\('..\/..\/config\/environment', __FILE__\)/, "File.expand_path(\"../dummy/config/environment\", __FILE__)")

# Test run RSpec
run_shell_command("rspec")

puts "INFO: #{gem_name} set up complete! Congratulations!"
puts "  run `cd #{gem_name}` to start building your gem."