Fix swagger-api integration after last update

See also:

* https://github.com/rswag/rswag/pull/668

config/initializers/rswag_api.rb

@@ -5,7 +5,7 @@ Rswag::Api.configure do |config|
   # This is used by the Swagger middleware to serve requests for API descriptions
   # NOTE: If you're using rswag-specs to generate Swagger, you'll need to ensure
   # that it's configured to generate files in the same folder
-  config.swagger_root = Rails.root.join("swagger")
+  config.swagger_root = Rails.root.join("swagger").to_s
 
   # Inject a lamda function to alter the returned Swagger prior to serialization
   # The function will have access to the rack env for the current request

spec/requests/api_docs_spec.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe "API documentation", type: :request do
+  it "shows the OFN API v1" do
+    get rswag_ui_path
+    expect(response).to redirect_to "/api-docs/index.html"
+
+    get "/api-docs/index.html"
+    expect(response).to have_http_status :success
+
+    expect(response.body).to match "API V1"
+  end
+
+  it "can load the Swagger config" do
+    get "/api-docs/v1/swagger.yaml"
+    expect(response).to have_http_status :success
+  end
+end