```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'paperclip_optimizer/version'

Gem::Specification.new do |spec|
  spec.name          = "paperclip-optimizer"
  spec.version       = PaperclipOptimizer::VERSION
  spec.authors       = ["Jan-Christian Föh"]
  spec.email         = ["jan@programmanstalt.de"]
  spec.description   = %q{paperclip-optimizer is a processor for Paperclip that allows you to optimize and minify uploaded JPEG and PNG files.}
  spec.summary       = %q{Minify Paperclip JPEG and PNG attachments}
  spec.homepage      = ""
  spec.license       = "MIT"

  spec.add_dependency "paperclip", "~> 3.4.1"

  spec.add_development_dependency "bundler", "~> 1.3"
  spec.add_development_dependency "rake"
  spec.add_development_dependency 'rspec'
  spec.add_development_dependency 'activerecord'
  spec.add_development_dependency 'sqlite3'

  spec.add_runtime_dependency "paperclip"

  spec.files         = `git ls-files`.split($/)
  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
  spec.require_paths = ["lib"]
end
```

Add Rails as a dependency for testing
user
```ruby
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'paperclip_optimizer/version'

Gem::Specification.new do |spec|
  spec.name          = "paperclip-optimizer"
  spec.version       = PaperclipOptimizer::VERSION
  spec.authors       = ["Jan-Christian Föh"]
  spec.email         = ["jan@programmanstalt.de"]
  spec.description   = %q{paperclip-optimizer is a processor for Paperclip that allows you to optimize and minify uploaded JPEG and PNG files.}
  spec.summary       = %q{Minify Paperclip JPEG and PNG attachments}
  spec.homepage      = ""
  spec.license       = "MIT"

  spec.add_dependency "paperclip", "~> 3.4.1"
  spec.add_dependency "image_optim", "~> 0.8"

  spec.add_development_dependency "bundler", "~> 1.3"
  spec.add_development_dependency "rake"
  spec.add_development_dependency 'rspec'
  spec.add_development_dependency 'rails'
  spec.add_development_dependency 'sqlite3'

  spec.add_runtime_dependency "paperclip"

  spec.files         = `git ls-files`.split($/)
  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
  spec.require_paths = ["lib"]
end
```
assistant