Proof of Concept for interactive creation of characterization tests

c11r.rb

# Written by Michael Feathers July 10th, 2020

class Command
  def run line, session
    return unless matches? line
    process line, session
  end
end

class FixView < Command
  def matches? line
    line.split == ["fix"]
  end

  def process line, session
    session.fix_view
  end
end

class FixNew < Command
  def matches? line
    line.split == ["fix","new"]
  end

  def process line, session
    session.fix_new
  end
end

class FixAdd < Command
  def matches? line
    line.split.take(2) == ["fix", "add"]
  end

  def process line, session
    session.fix_add(line.split.drop(2).join(" "))
  end
end

class FixRemove < Command
  def matches? line
    line.split.take(2) == ["fix", "remove"]
  end

  def process line, session
    session.fix_remove
  end
end

class Ask < Command
  def matches? line
    line.split.take(1) == ["ask"]
  end

  def process line, session
    session.ask(line.split.drop(1).join(" "))
  end
end

class Push < Command
  def matches? line
    tokens = line.split
    tokens.count >= 2 && tokens[0] == "push"
  end

  def process line, session
    session.push(line.split.drop(1).join(" "))
  end
end

class C11R

  @@commands = [FixNew.new, 
     FixView.new, 
     FixAdd.new, 
     FixRemove.new,
     Ask.new, 
     Push.new]

  def initialize
    @session = Session.new
  end

  def run
    ARGF.each_line {|li| on_line(li) }
  end

  def on_line line
    puts line
    @@commands.each {|c| c.run(line, @session) }
  end
end

class Session

  def fix
    @fix.join("; ") 
  end

  def initialize
    fix_new 
  end

  def fix_new
    @fix = []
    @question = @answer = ""
  end

  def fix_view
    puts "> " + fix 
  end

  def fix_add line
    @fix << line
  end

  def fix_remove
    @fix = @fix[0..-2]
  end

  def ask line
    @question = line
    @answer = (eval [@fix, @question].join("; ")).to_s
    puts "> " + @answer
    @answer
  end

  def push line
    puts "> test \"#{line}\""
    puts ">   #{fix}"
    puts ">   assert_eq(#{@answer},#{@question}))" unless (@answer.empty? || @question.empty?)
    puts "> end"
    @question = @answer = ""
  end
end


C11R.new.run