Example of using bundler/inline

README.md

I came across 'bundler/inline' in Bundler pull request 3440, which I'd found from Rails pull request 20429. This now has a little snippet on the What's new page of the Bundler site.

This little example demonstrates how I might use it to create a single file using minitest.

I've just noticed that this script was working for me because I already had minitest installed as a system gem. If I uninstall the gem then the script fails because it can't find minitest. The source code documents an option to install gems if they don't exist (gemfile(true) do) but that doesn't seem to work for me. I see the following error:

Fetching gem metadata from https://rubygems.org/...
Fetching version metadata from https://rubygems.org/..
Resolving dependencies...
Using metaclass 0.0.4

ArgumentError: different prefix: "" and "/Users/chrisroos/tmp/wem/.bundle/bin"
Bundler::InstallError: An error occurred while installing metaclass (0.0.4), and Bundler cannot continue. Make sure that `gem install metaclass -v '0.0.4'` succeeds before bundling.

I've now realised that the install option doesn't work because my bundler config is set to install gems to ./.bundle. If I ignore my bundler config then the gem is installed as expected:

BUNDLE_IGNORE_CONFIG=true ruby example-test-using-bundler-inline.rb 

example-test-using-bundler-inline.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'minitest', require: false
end

require 'minitest/autorun'

class MyTest < Minitest::Test
  def test_should_be_true
    assert_equal true, true
  end
end