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Bundler Development setup

To work on Bundler, you’ll probably want to do a couple of things:

  • Fork the Rubygems repo, and clone the fork onto your machine. (Follow this tutorial for instructions on forking a repo.)

  • Install graphviz package using your package manager:

      $ sudo apt-get install graphviz -y

    And for OS X (with brew installed):

      $ brew install graphviz
  • Install development dependencies from the rubygems root directory:

      $ rake setup
  • Change into the bundler directory:

      $ cd bundler
  • Install Bundler’s test dependencies:

      $ bin/rake spec:parallel_deps
  • Now you can run the test suite in parallel:

      $ bin/parallel_rspec
  • Set up a shell alias to run Bundler from your clone, e.g. a Bash alias (follow these instructions for adding aliases to your ~/.bashrc profile):

      $ alias dbundle='ruby /path/to/bundler/repo/spec/support/bundle.rb'

Jointly developing on Bundler and RubyGems

When developing Bundler features or bug fixes that require changes in RubyGems, you can make sure Bundler’s test suite picks up those changes by setting the RGV environment variable to point to the root of the repository, like this:

RGV=.. bin/parallel_rspec

It’s a good idea to make sure that your changes always work against the latest RubyGems, so setting this variable permanently might be a good idea. You can use direnv for that.

The RGV environment variable can also be set to arbitrary RubyGems versions, to make sure your changes in Bundler work fine with those versions. For example,

RGV=v3.2.33 bin/parallel_rspec

Debugging with pry

To dive into the code with Pry: RUBYOPT=-rpry dbundle to require pry and then run commands.

For background context: you can manipulate environment variables in Ruby to control the Ruby interpreter’s behavior. Ruby uses the RUBYOPT environment variable to specify options to launch Ruby with.

The arguments of RUBYOPT are applied as if you had typed them as flags after ruby. The -r flag means ‘require’. So saying -rpry means require 'pry'. To illustrate, ruby -rpry /path/to/bundle is the same as RUBYOPT=-rpry ruby /path/to/bundle.

So, RUBYOPT=-rpry dbundle is saying “require pry and require this path to Bundler”, which means that you will start your development environment with pry and your local bundler.

Why is this necessary? Why isn’t require 'pry'; binding.pry enough?

The reason for combining RUBYOPT with dbundle is because Bundler takes over what gems are available. If you have pry installed on your machine but not included in the Gemfile, Bundler itself will remove pry from the list of gems you can require. Setting RUBYOPT=-rpry is a way to require pry before Bundler takes over and removes it from the list of gems that can be required. That way, later, you can take advantage of binding.pry and have it work. Unfortunately, if you waited until the point of binding.pry to require 'pry', it would fail anytime pry is not in the Gemfile.

Edit this document on GitHub if you caught an error or noticed something was missing.