Mark Chavez

Binstubs are executable programs that act as a wrapper to their original executables. Let’s use rspec for example. RSpec, by default, has an available executable that we can use.

# Generate binstub for rspec
bundle binstubs rspec-core

This command will add the executable rspec to our project under the bin directory.

# run all tests
bin/rspec spec

It’s best practice to always use the executable provided from the bin directory. Running the binstub essentially means that we want to use the rspec version that the project is using. Doing otherwise would mean it will run the latest version of rspec in our local machine so we don’t want this.

An alternative to running a binstub executable is by prepending bundle exec to the command.

# No binstub, no problem!
bundle exec rspec spec

It accomplishes the same goal as the binstub — but you wouldn’t want to type it every time you need to run the tests. Nonetheless, you can use the method you prefer.

To generate binstubs contained in your project’s Gemfile

# generate executables!
bundle install --binstubs

# for a single gem
bundle binstubs rspec-core
bundle binstubs rake
bundle binstubs rails