Update tag task to update changelog

Author: nmburgan

tasks/tag.rake

@@ -2,6 +2,16 @@ namespace :vox do
   desc 'Create tag and push to origin'
   task :tag, [:tag] do |_, args|
     abort 'You must provide a tag.' if args[:tag].nil? || args[:tag].empty?
+    version = args[:tag]
+    abort "#{version} does not appear to be a valid version string in x.y.z format" unless Gem::Version.correct?(version)
+
+    # Changed unreleased to new version in CHANGELOG.md
+    puts 'Updating CHANGELOG.md'
+    data = File.read('CHANGELOG.md')
+    data = data.sub(/## Unreleased/, "## #{version}")
+    data = "## Unreleased\n\n" + data
+    File.write('CHANGELOG.md', data)
+    run_command("git add CHANGELOG.md && git commit -m 'Update changelog for #{version}'")
 
     # Run git command to get short SHA and one line description of the commit on HEAD
     branch = run_command('git rev-parse --abbrev-ref HEAD')
@@ -12,8 +22,11 @@ namespace :vox do
     puts "SHA: #{sha}"
     puts "Commit: #{msg}"
 
-    run_command("git tag -a #{args[:tag]} -m '#{args[:tag]}'")
-    puts "Pushing #{args[:tag]} to origin"
-    run_command("git push origin #{args[:tag]}")
+    run_command("git tag -a #{version} -m '#{version}'")
+
+    unless !ENV['NOPUSH'].nil?
+      puts "Pushing #{version} to origin"
+      run_command("git push origin #{version}")
+    end
   end
 end