Generate pretty reports of Gemfile.lock.diffs

bundle_differ.rb

#!/usr/bin/env ruby
 # Pretty print how the versions of gems changed between diffs of Gemfile.lock
 # usage: ./bundle_differ.rb path/to/Gemfile.lock.diff
 #
 # Example Output:
 #   ffi             1.9.0 -> 1.9.3
 #   guard           2.1.1 -> 2.2.2
 #   jquery-ui-rails 4.0.5 -> 4.1.0
 #   listen          2.1.1 -> 2.2.0
 #   uglifier        2.2.1 -> 2.3.0
 #   unf             0.1.2 -> 0.1.3

 def top_level?(line)
   spaces = line =~ /^.(\s+)/
   return false unless $1
   scope = $1.length
   scope == 4
 end

 # get rid of -+ and leading spaces
 def normalize_format(line)
   line.gsub(/^(-|\+)\s+/,"")
 end

 # takes an array like:
 # ["ffi (1.9.0)", "guard (2.1.1)", "jquery-ui-rails (4.0.5)", "listen (2.1.1)", "uglifier (2.2.1)", "unf (0.1.2)"]
 # and turns it into a hash like { :name => version }
 def gem_lines_to_hash(lines)
   lines.reduce({}) do |gems,line|
     name,version = line.split(" ")
     version.gsub!(/[\(\)]/,'')
     gems[name] = version
     gems
   end
 end

 diff_filename = ARGV.shift

 diff = if diff_filename
   File.read(diff_filename)
 else
   STDIN.read
 end


 old_lines = []
 new_lines = []

 diff.each_line do |line|
   line.chomp!
   case line
   when /^- / # Starts with a '-'. Was removed
     next unless top_level?(line)
     old_lines << normalize_format(line)
   when /^\+ / # Starts with a '+'. was added.
     next unless top_level?(line)
     new_lines << normalize_format(line)
   else
     # Skip the line
   end
 end

 old_gems = gem_lines_to_hash(old_lines)

 new_gems = gem_lines_to_hash(new_lines)

 # make a list of names we need to print.
 # Be sure to account for old gems that were removed and new gems that were just added
 gem_names = (old_gems.keys + new_gems.keys).uniq

 # Find the longest key so we can right justify the version changes
longest_name    = gem_names.max_by { |i| i.length }.length
longest_version = (old_gems.values + new_gems.values).max_by { |i| i.length}.length

gem_names.each do |gem_name|
  printf("%-#{longest_name}s %-#{longest_version}s -> %-#{longest_version}s\n", gem_name, old_gems[gem_name], new_gems[gem_name])
end