Add some tests for the help command
user
```ruby
require 'spec_helper'

describe Tugboat::CLI do
  include_context "spec"

  describe "help" do
    it "shows a help message" do
      @cli.help
      expect($stdout.string).to match("Commands:")
    end

    it "shows a help message for specific commands" do
      @cli.help "sizes"
      expect($stdout.string).to match("Usage:")
    end
  end
end
```
assistant