```ruby
Gem::Specification.new do |s|
  s.name = 'nexmo'
  s.version = '2.0.0'
  s.platform = Gem::Platform::RUBY
  s.authors = ['Tim Craft']
  s.email = ['mail@timcraft.com']
  s.homepage = 'http://github.com/timcraft/nexmo'
  s.description = 'A Ruby wrapper for the Nexmo API'
  s.summary = 'See description'
  s.files = Dir.glob('{lib,spec}/**/*') + %w(README.md nexmo.gemspec)
  s.required_ruby_version = '>= 1.9.3'
  s.add_development_dependency('rake', '~> 10.1')
  s.add_development_dependency('webmock', '~> 1.18')
  s.require_path = 'lib'
end
```

Add minitest as a development dependency
user
```ruby
Gem::Specification.new do |s|
  s.name = 'nexmo'
  s.version = '2.0.0'
  s.platform = Gem::Platform::RUBY
  s.authors = ['Tim Craft']
  s.email = ['mail@timcraft.com']
  s.homepage = 'http://github.com/timcraft/nexmo'
  s.description = 'A Ruby wrapper for the Nexmo API'
  s.summary = 'See description'
  s.files = Dir.glob('{lib,spec}/**/*') + %w(README.md nexmo.gemspec)
  s.required_ruby_version = '>= 1.9.3'
  s.add_development_dependency('rake', '~> 10.1')
  s.add_development_dependency('webmock', '~> 1.18')
  s.add_development_dependency('minitest', '~> 5.0')
  s.require_path = 'lib'
end
```
assistant