Zip a directory in memory with ruby

zippable.rb

require 'find'
require 'zip'

module Zippable
  def to_zip
    return zipped_file_path if File.exists? zipped_file_path
    validate_file_exists

    ::Zip::File.open(zipped_file_path, ::Zip::File::CREATE) do |zipfile|
      if File.directory? file_path
        Find.find(file_path).each do |file|
          zipfile.add(file.sub(file_path + '/', ''), file) if File.file? file
        end
      else
        zipfile.add(file_name, file_path)
     end
    end
    ::File.chmod(0664, zipped_file_path)
    zipped_file_path
  end

  private

  def file_path
    raise NotImplementedError, "#{self.class} does not implement the file_path method"
  end

  def file_name
    File.basename(file_path)
  end

  def zipped_file_path
    @zipped_file_path ||= "#{ENV['ZIPPED_FILES_DIR']}/#{file_name}.zip"
  end

  def validate_file_exists
    unless File.exists? file_path
      raise InvalidFileError, "this instance of #{self.class} has an invalid file_path"
    end
  end
end

zippable_spec.rb

require 'rails_helper'

class IncludesZippable
  include Zippable
  attr_reader :name, :dir
  def initialize(name, dir)
    @name = name
    @dir  = dir
  end

  def file_path
    File.join(dir, name)
  end
end

describe Zippable do
  let(:base_dir) { File.expand_path("../../fixtures/files", __FILE__) }
  let(:file) { "zippable_file.mp3" }
  let(:dir) { "zippable_dir" }
  let(:brackets) { "Dir.with.dots [123]" }

  subject { IncludesZippable.new(name, base_dir) }

  before :all do
    `mkdir -p "#{ENV['ZIPPED_FILES_DIR']}"`
  end

  before do
    delete_tmp_file(name)
  end

  shared_examples_for "the zip file exists" do
    it {
      subject.to_zip
      expect(File.exists? zipped_file_path(name)).to be true
    }
  end

  context "zipping a file" do
    let(:name) { file }

    it_behaves_like "the zip file exists"

    it "returns a zipped file" do
      expect(subject.to_zip).to eql("#{ENV['ZIPPED_FILES_DIR']}/zippable_file.mp3.zip")
    end
  end

  context "zipping a directory" do
    let(:name) { dir }

    it_behaves_like "the zip file exists"

    it "returns a zipped file" do
      expect(subject.to_zip).to eql("#{ENV['ZIPPED_FILES_DIR']}/zippable_dir.zip")
    end
  end

  context "the zipped file exists" do
    let(:name) { file }

    before do
      File.stub(:exists?).with("#{ENV['ZIPPED_FILES_DIR']}/#{name}.zip").and_return(true)
    end

    it_behaves_like "the zip file exists"

    it "returns the existing zipped file" do
      expect(subject.to_zip).to eql("#{ENV['ZIPPED_FILES_DIR']}/zippable_file.mp3.zip")
    end
  end

  context "zipping a missing file" do
    let(:name) { "bogus" }

    it { expect { subject.to_zip }.to raise_error(InvalidFileError,
      "this instance of IncludesZippable has an invalid file_path")
    }
  end

  context "zipping a directory with dots and brackets" do
    let(:name) { brackets }

    it_behaves_like "the zip file exists"

    it "returns a zipped file" do
      expect(subject.to_zip).to eql("#{ENV['ZIPPED_FILES_DIR']}/Dir.with.dots [123].zip")
    end
  end
end

def delete_tmp_file(name)
  File.delete(zipped_file_path(name)) if File.exist?(zipped_file_path(name))
end

def zipped_file_path(name)
  "#{ENV['ZIPPED_FILES_DIR']}/#{name}.zip"
end