[feature:gem] Add gem:release rake task (#36)

Rakefile

@@ -1,11 +1,65 @@
+require 'thor'
 require 'bundler/gem_tasks'
 require 'rspec/core/rake_task'
 RSpec::Core::RakeTask.new :spec
 
 desc 'Run application specs'
 task default: [:spec]
 
-desc 'Debug the gem (load into IRB)'
-task :debug do
-  exec 'bundle exec rake install && irb -I lib/arx.rb -r arx'
+namespace :gem do
+  class T < Thor
+    include Thor::Actions
+  end
+
+  desc 'Debug the gem (load into IRB)'
+  task :debug do
+    exec 'bundle exec rake install && irb -I lib/arx.rb -r arx'
+  end
+
+  desc 'Prepare a new gem release'
+  task :release, %i[major minor patch meta] do |task, args|
+    array = args.to_a
+    raise ArgumentError.new("Expected at least 3 SemVer segments, got #{array.size}") if array.size < 3
+    raise ArgumentError.new("Expected no more than 4 SemVer segments, got #{array.size}") if array.size > 4
+    args.to_h.each_with_index do |(segment, value), index|
+      next if index == array.size - 1 && array.size == 4
+      raise TypeError.new("Invalid #{segment} SemVer segment: #{value}") unless value == value.to_i.to_s
+    end
+
+    versions = args.to_h.transform_values {|v| v.to_i if Integer(v) rescue v}
+    versions[:meta] ||= nil
+    update_version versions
+
+    version = versions.compact.values.join('.')
+    add_changelog_entry version
+  end
+
+  private
+
+  def update_version(versions)
+    versions.each do |segment, value|
+      thor :gsub_file, File.join(__dir__, 'lib', 'arx', 'version.rb'), /#{segment}: .*,/, "#{segment}: #{value.inspect},"
+    end
+  end
+
+  def add_changelog_entry(version)
+    thor :insert_into_file, File.join(__dir__, 'CHANGELOG.md'), after: /\A/ do
+      <<-ENTRY
+# #{version}
+
+#### Major changes
+
+- TODO
+
+#### Minor changes
+
+- TODO
+
+      ENTRY
+    end
+  end
+
+  def thor(*args, &block)
+    T.new.send *args, &block
+  end
 end

arx.gemspec

@@ -23,6 +23,7 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency 'bundler', '~> 2.0'
   spec.add_development_dependency 'rake', '~> 12.3'
+  spec.add_development_dependency 'thor', '~> 0.20'
   spec.add_development_dependency 'rspec', '~> 3.7'
 
   spec.metadata = {

lib/arx/version.rb

@@ -7,6 +7,6 @@ module Arx
     major: 0,
     minor: 3,
     patch: 1,
-    meta: nil
+    meta: nil,
   }.compact.values.join('.').freeze
 end