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Development setup

Bundler doesn’t use a Gemfile to list development dependencies, because when we tried it we couldn’t tell if we were awake or it was just another level of dreams. To work on Bundler, you’ll probably want to do a couple of things:

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

  2. Install groff-base and graphviz packages using your package manager, e.g for Ubuntu:

    $ sudo apt-get install graphviz groff-base -y

    and for OS X (with brew installed):

    $ brew install graphviz homebrew/dupes/groff

  3. Install Bundler’s development dependencies:

    $ bin/rake spec:deps

  4. Run the test suite, to make sure things are working:

    $ bin/rake spec

  5. 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='/path/to/bundler/repo/bin/bundle'

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.