Use inline Oj settings when necessary (#2)

Setting `Oj.default_options` global setting causes unexpected sid effects for applications where gem is being included. Instead the `bigdecimal_load: :bigdecimal` mode can be applied inline.

avatax.gemspec

@@ -4,6 +4,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency('rake', '~> 12.0.0')
   s.add_development_dependency('rspec', '~> 3.5.0')
   s.add_development_dependency('webmock', '>= 2.0.0')
+  s.add_development_dependency('pry')
   s.add_runtime_dependency('faraday', '>= 0.10')
   s.add_runtime_dependency('faraday_middleware', '>= 0.10')
   s.add_runtime_dependency('multi_json', '>= 1.0.3')

lib/avatax/api.rb

@@ -3,7 +3,6 @@
 
 module AvaTax
   class API
-
     attr_accessor *Configuration::VALID_OPTIONS_KEYS
 
     def initialize(options={})

lib/avatax/connection.rb

@@ -1,8 +1,20 @@
+require 'faraday_middleware/response_middleware'
 require 'faraday_middleware/parse_oj'
 
 module AvaTax
-
   module Connection
+    module FaradayMiddleware
+      class ParseOjWithBigDecimal < ::FaradayMiddleware::ResponseMiddleware
+        dependency 'oj'
+
+        define_parser do |body|
+          Oj.load(body, mode: :compat, bigdecimal_load: :bigdecimal) unless body.strip.empty?
+        end
+      end
+    end
+
+    Faraday::Response.register_middleware oj_with_bigdecimal: FaradayMiddleware::ParseOjWithBigDecimal
+
     private
     AUTHORIZATION_FILTER_REGEX = /(Authorization\:\ \"Basic\ )(\w+)\=/
     REMOVED_LABEL = '\1[REMOVED]'
@@ -22,13 +34,13 @@ def connection
       }.merge(connection_options)
 
       Faraday.new(options) do |faraday|
-        if Gem::Version.new(RUBY_VERSION) > Gem::Version.new('2.2.2') and response_big_decimal_conversion
-          Oj.default_options = {
-            bigdecimal_load: :bigdecimal
-          }
-        end
+        faraday_response_parser = if Gem::Version.new(RUBY_VERSION) > Gem::Version.new('2.2.2') and response_big_decimal_conversion
+                                    :oj_with_bigdecimal
+                                  else
+                                    :oj
+                                  end
 
-        faraday.response :oj, content_type: /\bjson$/
+        faraday.response faraday_response_parser, content_type: /\bjson$/
         faraday.basic_auth(username, password)
 
         if logger

spec/avatax/api_spec.rb

@@ -0,0 +1,30 @@
+require_relative "../spec_helper"
+
+describe AvaTax::API do
+  context "connection" do
+
+    it "uses custom ParseOj for regular config" do
+      faraday_instance_double = double.as_null_object
+
+      expect(Faraday).to receive(:new).and_yield(faraday_instance_double)
+      expect(faraday_instance_double).to receive(:response).with(:oj, { content_type: /\bjson$/ })
+
+      # default setting
+      expect(Oj.default_options[:bigdecimal_load]).to eq(:auto)
+
+      AvaTax::API.new.send(:connection)
+    end
+
+    it "uses custom ParseOjWithBigDecimal when response_big_decimal_conversion provided" do
+      faraday_instance_double = double.as_null_object
+
+      expect(Faraday).to receive(:new).and_yield(faraday_instance_double)
+      expect(faraday_instance_double).to receive(:response).with(:oj_with_bigdecimal, { content_type: /\bjson$/ })
+
+      # default setting
+      expect(Oj.default_options[:bigdecimal_load]).to eq(:auto)
+
+      AvaTax::API.new(response_big_decimal_conversion: true).send(:connection)
+    end
+  end
+end

spec/spec_helper.rb

@@ -22,6 +22,6 @@
 RSpec.configure do |config|
   config.before {
     @client = client
-    @company_code = companies["value"][0]["companyCode"]
+    @company_code = companies.dig("value", 0, "companyCode")
   }
 end