installation_satisfies_dependency?

# File lib/rubygems/installer.rb, line 392
  def installation_satisfies_dependency?(dependency)
    return true if @options[:development] and dependency.type == :development
    return true if installed_specs.detect { |s| dependency.matches_spec? s }
    return false if @only_install_dir
    not dependency.matching_specs.empty?
  end