npm_spec.rb

require 'fileutils'

NPM_2 = File.expand_path('./npm/2.15.2/package/bin/npm-cli.js')
NPM_3 = File.expand_path('./npm/3.8.5/package/bin/npm-cli.js')

describe 'npm', :vcr do
  def run!(*command)
    Kernel.system(*command) || raise("Command exited with status #{$?}")
  end

  around do |example|
    Dir.mktmpdir do |tmpdir|
      FileUtils.copy('package.json', tmpdir)
      Dir.chdir(tmpdir) do
        example.run
      end
    end
  end

  def current_shrinkwrap_json
    File.read('npm-shrinkwrap.json')
  end

  describe 'version 2' do
    let(:npm) do
      NPM_2
    end

    describe 'npm install --save' do
      it 'does not update npm-shrinkwrap.json' do
        run!(npm, 'shrinkwrap')
        initial_shrinkwrap = current_shrinkwrap_json
        run!(npm, 'install', '--save', 'lodash')
        expect(current_shrinkwrap_json).to eq(initial_shrinkwrap)
      end
    end
  end

  describe 'version 3' do
    let(:npm) do
      NPM_3
    end

    describe 'npm install --save' do
      it 'updates npm-shrinkwrap.json' do
        run!(npm, 'shrinkwrap')
        initial_shrinkwrap = current_shrinkwrap_json
        run!(npm, 'install', '--save', 'lodash')
        expect(current_shrinkwrap_json).not_to eq(initial_shrinkwrap)
      end
    end
  end
end