Release code diffs

We first need to look at where the code is from. In looking at gemfiles we found how to see what gem you are currently working with, and in looking and package.json we did the same for npm. The logic in the same once we have

1. Repo
2. Original tag
3. New tag

For testing purposes, we are assuming that you've pulled this information out from your package manager and we know that

We'll start by cloning or updating the repo into a directory. In this case, the repo will go into /tmp/middleman/repo. Our analysis will go in /tmp/middleman.

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  require 'pp'

  WORKDIR='/tmp'

  repo='https://github.com/middleman/middleman'
  current_version='4.3.3'
  new_version='4.3.9'

  def load_repo repo
    dir = repo.gsub( /.*\//, "" )
    repo_dir = "#{WORKDIR}/#{dir}/repo"

    if File.exists? repo_dir
      system( "cd #{repo_dir};git pull origin master" )
    else
      system( "mkdir -p #{WORKDIR}/#{dir}" )
      system( "cd #{WORKDIR}/#{dir};git clone #{repo} repo" )
    end

    repo_dir
  end

  repo_dir = load_repo( repo )

  puts "Repo directory: #{repo_dir}"

Repo directory: /tmp/middleman/repo

Now that we have the repo, we need to find the tags in the project. We'll pull down a list of all the tags in the project.

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  latest_tags = `cd #{repo_dir};git tag --sort=-v:refname`.lines.collect { |x| x.chomp }

  puts "latest_tag : #{latest_tags.first}"

latest_tag : v5.0.0.rc.1

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  require 'bundler/inline'

  gemfile do
    source 'https://rubygems.org'
    gem 'semver2', '3.4.2', require: 'semver'
  end

  tag_info = latest_tags.collect { |tag| SemVer.parse_rubygems tag }

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  releases = tag_info.select { |x| x.prerelease == "" }
  puts "latest_release : #{releases.first}"

latest_release : v4.3.10

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  def find_tag tag_info, latest_tags, version_string
    version = SemVer.parse_rubygems version_string
  
    tag_info.each_with_index do |tag, idx|
      if tag == version
        return latest_tags[idx]
      end
    end

    nil
  end

  current_tag = find_tag tag_info, latest_tags, current_version
  new_tag = find_tag tag_info, latest_tags, new_version

  if current_tag.nil?
    puts "Couldn't find current_version #{current_version}"
  end

  if new_tag.nil?
    puts "Couldn't find new_version #{new_version}"
  end

  if current_tag.nil? || new_tag.nil?
    exit 1
  end

  puts "current_tag: #{current_tag}"
  puts "new_tag    : #{new_tag}"

current_tag: v4.3.3
new_tag    : v4.3.9

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  def find_latest_patch tag_info, version_string
    version = SemVer.parse_rubygems version_string

    tag_info.each do |tag|
      return tag if tag.major == version.major && tag.minor = version.minor
    end

    nil
  end

  highest_patch = find_latest_patch tag_info, new_tag
  puts "most compatible patch: #{highest_patch}"

most compatible patch: v4.3.10

Now that we have identified the tags, we can start to ask questions about what happened between those two results. We'll use the git log command, which is amazingly powerful and super cool.

Super cool. You heard me.

These are the formatting options that we'll be using:

We're going to output a log of the changes that happened between the tags. We'll have to do some crazy regex to pull out the fields.

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  git_cmd = "git log --reverse --pretty='format:%aI|%h|%ae|%an|%s' #{current_tag}..#{new_tag}"

  commits = `cd #{repo_dir};#{git_cmd}`.lines.collect do |x|
    x.chomp
    md = /(.*?)\|(.*?)\|(.*?)\|(.*?)\|(.*)/.match( x )
    { date: md[1], hash: md[2], email: md[3], name: md[4], summary: md[5] }
  end

  puts "Most recent change: #{commits.first[:date]}"
  puts "Oldest change     : #{commits.last[:date]}"

Most recent change: 2018-01-20T08:26:10+09:00
Oldest change     : 2020-09-09T14:06:57-07:00

We can can calculate how many days have passed bewteen the releases like so

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require 'time'
oldest = Time.parse( commits.first[:date] )
newest = Time.parse( commits.last[:date] )
days_passed = (newest - oldest) / (60 * 60 * 24) # Seconds in a day

puts "Days passed : #{days_passed}"

Days passed : 963.9033217592593

Which is a bit unnecessarily precise but gives you a sense of all the years that have gone by.

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issues = commits.collect do |commit|
  md = /\#([^\s\)\]]*)/.match( commit[:summary] )
  md ? md[1] : nil
end.select { |x| x }.sort

pp issues

["2083", "2143", "2287", "2316", "2323", "2327", "2348"]

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  changes = {}

  if File.exists? "#{repo_dir}/CHANGELOG.md"
    scan_version = nil
    entries = []
    headline_re = /\#{1,3} (.*)/

    File.read( "#{repo_dir}/CHANGELOG.md" ).each_line do |line|
      line.chomp!
      md = headline_re.match( line )
      if md
        if current_version && entries.length > 0
          changes[scan_version] = entries
          entries = []
        end
        scan_version = md[1]
      elsif line != ""
        entries << line
      end
    end

    if current_version && entries.length > 0
      changes[scan_version] = entries
    end
  end

  if changes[new_version]
    puts "Found change log for #{new_version}"
  else
     puts "No entry for #{new_version}"
  end

  if changes[current_version]
    puts "Found change log for #{current_version}"
  else
   puts "No entry for #{current_version}"
  end

No entry for 4.3.9
Found change log for 4.3.3

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cd /tmp/middleman/repo
git shortlog -n v4.3.3..v4.3.9

Thomas Reynolds (13):
      Bump minor
      Lock old bundler
      Disable bind test on travis
      Update changelog [ci skip]
      Prep
      Add Ruby 2.7.0 to CI
      Prepare 4.3.6
      Disable therubyracer
      Bump
      Prep release
      Update changelog
      Fix #2083
      Prep 4.3.9

Alexey Vasiliev (1):
      Update kramdown to avoid CVE-2020-14001 in v4 (#2348)

Johnny Shields (1):
      Fix ignore of I18n files (#2143)

Julik Tarkhanov (1):
      Reset Content-Length header when rewriting (#2316)

Leigh McCulloch (1):
      Loosen activesupport dependence (#2327)

Maarten (1):
      Fix i18n with anchor v4 (#2287)

bravegrape (1):
      Add empty image alt tag if alt text not specified (#2323)

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cd /tmp/middleman/repo
git shortlog -n -s v4.3.3..v4.3.9

    13	Thomas Reynolds
     1	Alexey Vasiliev
     1	Johnny Shields
     1	Julik Tarkhanov
     1	Leigh McCulloch
     1	Maarten
     1	bravegrape

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authors = {}
commits.each do |c|
  authors[c[:name]] ||= 0
  authors[c[:name]] += 1
end

authors.keys.sort { |a,b| authors[b] <=> authors[a] }.each do |author|
  printf "%10d %s\n", authors[author], author
end

       13 Thomas Reynolds
        1 Johnny Shields
        1 Maarten
        1 Julik Tarkhanov
        1 bravegrape
        1 Leigh McCulloch
        1 Alexey Vasiliev

Between the two versions we want to see everything that changed. We can do this using the git diff command, and pass in --numstat to see the files that changed.

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cd /tmp/middleman/repo
git diff --numstat v4.3.3..v4.3.9

18	0	.devcontainer/Dockerfile
37	0	.devcontainer/devcontainer.json
4	0	.travis.yml
29	0	CHANGELOG.md
2	2	Gemfile
17	24	Gemfile.lock
316	315	middleman-cli/features/preview_server.feature
11	0	middleman-core/features/default_alt_tag.feature
4	0	middleman-core/features/i18n_link_to.feature
67	11	middleman-core/features/ignore.feature
5	2	middleman-core/features/liquid.feature
17	0	middleman-core/features/markdown_kramdown.feature
1	1	middleman-core/features/relative_assets.feature
1	1	middleman-core/features/relative_assets_helpers_only.feature
0	0	middleman-core/fixtures/default-alt-tags-app/config.rb
1	0	middleman-core/fixtures/default-alt-tags-app/source/empty-alt-tag.html.erb
-	-	middleman-core/fixtures/default-alt-tags-app/source/images/blank.gif
1	0	middleman-core/fixtures/default-alt-tags-app/source/meaningful-alt-tag.html.erb
2	0	middleman-core/lib/middleman-core/core_extensions/default_helpers.rb
9	0	middleman-core/lib/middleman-core/core_extensions/i18n.rb
5	0	middleman-core/lib/middleman-core/core_extensions/inline_url_rewriter.rb
4	0	middleman-core/lib/middleman-core/renderers/kramdown.rb
1	1	middleman-core/lib/middleman-core/template_renderer.rb
1	1	middleman-core/lib/middleman-core/version.rb
1	1	middleman-core/middleman-core.gemspec
1	1	middleman/middleman.gemspec

--numstat shows you the lines of code added and deleted, and from this it looks like most of the work on the repo was in the test directory for a feature named preview server. The actual number of changes to the main source code seems pretty small, but if we want to take a look at what those changes are:

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cd /tmp/middleman/repo
git diff v4.3.3..v4.3.9 '*.rb'

Which shows a huge output of the diffs of all the code files from the one tag to the other. I'll spare you from scrolling through, but if we look just at the version.rb file you can see that it shows the diffs from where you start to where you end up – in this case, from version 4.3.3 to =4.3.9.

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cd /tmp/middleman/repo
git diff v4.3.3..v4.3.9 '*version.rb'

diff --git a/middleman-core/lib/middleman-core/version.rb b/middleman-core/lib/middleman-core/version.rb
index 42bc84bc..753d3c87 100644
--- a/middleman-core/lib/middleman-core/version.rb
+++ b/middleman-core/lib/middleman-core/version.rb
@@ -1,5 +1,5 @@
 module Middleman
   # Current Version
   # @return [String]
-  VERSION = '4.3.3'.freeze unless const_defined?(:VERSION)
+  VERSION = '4.3.9'.freeze unless const_defined?(:VERSION)
 end

Given a Gemfile.lock or a package-lock.json we can see which version of a module you are currently running, where the code is hosted, and which is the latest version. From here we can pull down the repo, look for the tags that marked each specific version, and see who worked on it and what the overall diffs are to see exactly what code has changed. This works if the code is hosted on github, or any other giy repository.

In addition to looking at the repositories between the tags, we can also also pull in static analysis for other parts of the project. We can put the gitlog in SQLite and do further analysis.

Each of these steps needs further refinement but we've got all of the major pieces together.

1. Semantic Versioning 2.0.0
2. Keep a changelong
3. git shortlog