> ## Documentation Index
> Fetch the complete documentation index at: https://docs.codecrafters.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Ruby

> Learn how to solve CodeCrafters challenges in Ruby

<Note> **New to Ruby?** We recommend [Ruby in Twenty Minutes](https://www.ruby-lang.org/en/documentation/quickstart/) to get up to speed.</Note>

## Local development

To run the code for your challenge locally, you'll need `ruby` installed. Our test runners use version `3.3` (as of May 2024).

The script for your challenge (like `./spawn_redis_server.sh`) will run your code using [Bundler](https://bundler.io/), a dependency manager which comes preinstalled with Ruby. It looks something like this:

```sh theme={null}
#!/bin/sh

exec bundle exec ruby app/main.rb "$@"
```

## File structure

* The files for your solution are placed in the `app/` directory.
* `app/main.rb` is the entrypoint of the project.

## Adding more files

You can add more files and directories to `app/`. The test runner will include them when compiling your code.

For example, if you added a file at `app/foo.rb`, you could use it like so:

<CodeGroup>
  ```Ruby app/main.rb theme={null}
  require_relative 'foo'

  foo();  # Calls foo() defined in app/foo.rb
  ```

  ```Ruby app/foo.rb theme={null}
  def foo
      puts "Hello world!"
  end
  ```
</CodeGroup>

## Adding dependencies

`Gemfile` lists your project's dependencies. You can add dependencies by specifying the name of the gem and optionally the version.

For example, To add the `nokogiri` gem, add the following line to your `Gemfile`:

```Gemfile theme={null}
gem 'nokogiri'
```

Then run the following command to install it:

```bash theme={null}
bundle install
```

This command will also update your `Gemfile.lock` file.