Use Gemfile instead of Gem::Specification#add_development_dependency

Author: hsbt

Gemfile

@@ -4,3 +4,9 @@ git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
 
 # Specify your gem's dependencies in ostruct.gemspec
 gemspec
+
+group :development do
+  gem "bundler"
+  gem "rake"
+  gem "test-unit"
+end

ostruct.gemspec

@@ -21,8 +21,4 @@ Gem::Specification.new do |spec|
 
   spec.files         = [".gitignore", "Gemfile", "LICENSE.txt", "README.md", "Rakefile", "bin/console", "bin/setup", "lib/ostruct.rb", "ostruct.gemspec"]
   spec.require_paths = ["lib"]
-
-  spec.add_development_dependency "bundler"
-  spec.add_development_dependency "rake"
-  spec.add_development_dependency "test-unit"
 end