How to Test Local Ruby Gems with Ease

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Sharing code between Ruby projects is simple when you package the code into gems. But keeping your local version synced to the development version can sometimes be a hassle.

While deploying updates as formal releases works for production, testing a gem locally with one of your projects requires a slightly different approach. Here’s an easy way to do it without creating unnecessary headaches:

One common way is to point your Gemfile to the local path of your gem:

gem "my_gem_name", path: "/user/my/projects/my_gem_name"

This replaces the version requirement (e.g., ~> 1.2) and lets Bundler use the local gem instead. However, be careful not to commit this change to avoid breaking your setup on other machines.

Using Bundler Config Instead

A better solution is to use Bundler’s configuration options to point to the local gem path:

To set this for all projects on your machine:

  bundle config local.my_gem_name ../projects/my_gem_name

To set this for the current project only:

  bundle config --local local.my_gem_name ../projects/my_gem_name

A Bonus Feature

If the git branch of your local gem version doesn’t match the Gemfile.lock, Bundler will throw a helpful error message. This ensures you catch potential issues early.

Now go forth and refactor with confidence, knowing your gems are synced and easy to manage!