A tool to display all branches that have dependancies in your repository and list out what branches have been merged and are therefore dependancies.

git-dependancies.rb

#!/usr/bin/env ruby

begin
  require 'rainbow'
rescue LoadError
  module Rainbow
    def color(color)
      self
    end
    def background(color)
      self
    end
  end
  String.send(:include, Rainbow)
end

class Branch
  def self.branches
    @@branches ||= Hash[
        `git branch -r`.split("\n")
          .map { |x| x.strip }
          .select { |x| x !~ /\bmaster\b/ }
          .map { |x| [x, Branch.new(x)] }
        ]
  end

  def initialize(base_name)
    @base_name = base_name.strip
  end

  def base_name
    @base_name
  end

  def name
    @name ||= @base_name.gsub(/^(heads|head|origin|remotes\/[^\/]+)\//, '').strip
  end

  def dependancies
    @dependancies ||= branch_dependancies
  end

  def description
    @description ||= `git log origin/master..#{base_name} --format="%B"`
  end

  def rev_list
    @rev_list ||= extract_rev_list(`git rev-list #{base_name} --not origin/master --format="%H"`)
  end
  
  def master_merge_base
    @master_merge_base ||= `git merge-base origin/master #{base_name}`.strip
  end

  def merge_base(branch)
    `git merge-base #{branch.base_name} #{base_name}`.strip
  end

  def behind(branch)
    extract_rev_list(`git rev-list #{branch.base_name} --not #{base_name}`).count
  end

private
  def branch_dependancies
    Branch.branches.select do |name, branch|
      if branch.base_name.eql?(base_name)
        false
      else
        if !rev_list.member?(merge_base(branch))
          false
        else
          #!master_merge_base.eql?(merge_base(branch))
          !((rev_list - branch.rev_list).empty?) && !(description.scan(branch.name).empty?)
        end
      end
    end
  end

  def extract_rev_list(data)
    data.split("\n")
      .select { |x| x !~ /^commit / }
      .map { |x| x.gsub(/commit /, '').split(' ').last.strip }
  end
end

puts "Branch dependancies:"

Branch.branches.each do |name, branch|
  if !branch.dependancies.empty?
    puts "  #{name}".color(:yellow)
    branch.dependancies.map do |sub_name, sub_branch|
      behind = branch.behind(sub_branch)
      color = :green
      if behind > 0
        color = :red
      end
      puts "    #{sub_branch.name}".color(color)
    end
    puts ""
  end
end