Add initial support for openapi v3

Author: adamrdavid

.github/workflows/build.yml

@@ -25,4 +25,4 @@ jobs:
         bundle exec rspec spec/
     - name: Lint with rubocop
       run: |
-        bundle exec rubocop --verbose && bundle exec rubocop
+        bundle exec rubocop

lib/open_api_parser/document.rb

@@ -4,7 +4,7 @@ module OpenApiParser
   class Document
     def self.resolve(path, file_cache = OpenApiParser::FileCache.new)
       file_cache.get(path) do
-        content = YAML.load_file(path)
+        content = YAML.safe_load(ERB.new(File.read(path)).result)
         Document.new(path, content, file_cache).resolve
       end
     end

lib/open_api_parser/specification.rb

@@ -2,17 +2,26 @@
 
 module OpenApiParser
   module Specification
-    META_SCHEMA_PATH = File.expand_path('../../resources/swagger_meta_schema.json', __dir__)
+    META_SCHEMA_PATH_2 = File.expand_path('../../resources/swagger_meta_schema_2.0.json', __dir__)
+    META_SCHEMA_PATH_3 = File.expand_path('../../resources/swagger_meta_schema_3.0.json', __dir__)
 
     def self.resolve(path, validate_meta_schema: true)
       raw_specification = Document.resolve(path)
 
       if validate_meta_schema
-        meta_schema = JSON.parse(File.read(META_SCHEMA_PATH))
+        meta_schema = JSON.parse(File.read(meta_schema_path(raw_specification)))
         JSON::Validator.validate!(meta_schema, raw_specification)
       end
 
       OpenApiParser::Specification::Root.new(raw_specification)
     end
+
+    def self.meta_schema_path(raw_specification)
+      if raw_specification.key?('openapi')
+        META_SCHEMA_PATH_3
+      else
+        META_SCHEMA_PATH_2
+      end
+    end
   end
 end