Support Static Path Prefix per Definition

[orionstudt]

Adds support for a static path_prefix value to be set on the creation of a Definition. The issue with the existing config.path function is that it needs to run at runtime for every single request, and that when there are many different possible prefixes it needs to account for all of them.

Imagine a Rails app built from many different engines. Engines like:

• root
• weather
• stocks
• analytics

These engines each provide APIs that have different scaling needs. So in a production environment, you will not deploy them together. They will each get their own domains like:

• api.example.com
• weather-api.example.com
• stocks-api.example.com
• analytics-api.example.com

However when you are running this Rails app locally you mount all of the engines to a single app, and configure them like:

• localhost:3000
• localhost:3000/weather
• localhost:3000/stocks
• localhost:3000/analytics

Furthermore, imagine that each of your engines have their own Open API document. In a scenario like this, in order to configure prefixes when running locally you would have to drop those prefixes from every request like:

OpenapiFirst.configure do |config|
  config.register('openapi/openapi.yaml')
  config.register('openapi/weather-openapi.yaml', as: :weather)
  config.register('openapi/stocks-openapi.yaml', as: :stocks)
  config.register('openapi/analytics-openapi.yaml', as: :analytics)
  config.path = lambda { |request|
    request.path.delete_prefix('/weather') if request.path.start_with?('/weather')
    request.path.delete_prefix('/stocks') if request.path.start_with?('/stocks')
    request.path.delete_prefix('/analytics') if request.path.start_with?('/analytics')
  }
end

But this has issues because:

1. We know what the prefix will be when we register the definition
2. The delete_prefix checks are going to run on every request, even for engines that don't care about the prefix being deleted
3. If the root engine has any endpoints that begin with /weather, /stocks, or /analytics they will lose the prefix when they shouldn't

So adding support for path_prefix on Definition load enables this to become:

OpenapiFirst.configure do |config|
  config.register('openapi/openapi.yaml')
  config.register('openapi/weather-openapi.yaml', as: :weather, path_prefix: '/weather')
  config.register('openapi/stocks-openapi.yaml', as: :stocks, path_prefix: '/stocks')
  config.register('openapi/analytics-openapi.yaml', as: :analytics, path_prefix: '/analytics')
end

And now the prefix only drops for the specific definition being evaluated.

[orionstudt]

Drive by re-naming to align with what validate_request already calls them since it is less verbose

[orionstudt]

this one wasn't actually testing because it was passing a request defined above that didn't have /prefix in the path

[ahx]

Thanks for the great description. Looks good to me. Can you add a changelog entry about this? (Just in the "Unreleased" section)