A Script to Check the Syntax of Ruby Files -- Based off of a git precommit hook

syntax_check.rb

#!/usr/bin/env ruby

require 'open3'
include Open3

skip_erb_files = true

compiler_ruby = `which rbx`.strip
compiler_ruby = `which ruby`.strip if compiler_ruby.length == 0

all_files = Dir["./**/**"]
changed_ruby_files = []
all_files.each do |file|
  changed_ruby_files << file if file =~ /(.+\.(e?rb|task|rake|thor)|[Rr]akefile|[Tt]horfile)/
end

problematic_files = changed_ruby_files.inject([]) do |problematic_files, file|
  if File.readable? file
    puts "checking #{file}"
    cmd = if file =~ /\.erb\z/
      # Set trim mode to "-", just as Rails does
      "erb -xT - #{file} | #{compiler_ruby} -wc" unless skip_erb_files
    else
      "#{compiler_ruby} -wc #{file}"
    end

    unless cmd.nil? then
      errors = nil
      popen3(cmd) do |stdin, stdout, stderr|
        errors = stderr.read.split("\n")
      end
  
      errors.reject!{ |line| line =~ /[0-9]+:\s+warning:/ } # unless stop_on_warnings
  
      unless errors.empty?
        errors.map!{ |line| line.sub(/#{file}:/, '') }
        problematic_files << "#{file}:\n#{errors.join("\n")}"
      end
    end
  end

  problematic_files
end

if problematic_files.size > 0
  $stderr.puts problematic_files.join("\n\n")
  exit 1
else
  # All is well
  exit 0
end