Do not use add_development_dependency.

Author: hsbt

Gemfile

@@ -1,3 +1,10 @@
 source 'https://rubygems.org'
 
 gemspec
+
+group :development do
+  gem 'rake-compiler', ">= 0.4.1"
+  gem 'minitest', "~> 5.0"
+  gem 'rake-compiler-dock', ">= 0.6.3", :platforms => :ruby
+  gem 'ruby-maven', :platforms => :jruby
+end

psych.gemspec

@@ -51,9 +51,6 @@ DESCRIPTION
   s.rubygems_version = "2.5.1"
   s.required_rubygems_version = Gem::Requirement.new(">= 0")
 
-  s.add_development_dependency 'rake-compiler', ">= 0.4.1"
-  s.add_development_dependency 'minitest', "~> 5.0"
-
   if RUBY_ENGINE == 'jruby'
     s.platform = 'java'
     s.files.concat [
@@ -67,9 +64,7 @@ DESCRIPTION
     ]
     s.requirements = "jar org.yaml:snakeyaml, #{Psych::DEFAULT_SNAKEYAML_VERSION}"
     s.add_dependency 'jar-dependencies', '>= 0.1.7'
-    s.add_development_dependency 'ruby-maven'
   else
     s.extensions = ["ext/psych/extconf.rb"]
-    s.add_development_dependency 'rake-compiler-dock', ">= 0.6.3"
   end
 end