Use constantize instead of Object.const_get

.rspec_status

 example_id                                 | status | run_time        |
 ------------------------------------------ | ------ | --------------- |
-./spec/shotengai/models_spec.rb[1:1:1:1]   | failed | 0.20529 seconds |
-./spec/shotengai/models_spec.rb[1:1:1:2]   | failed | 0.16928 seconds |
-./spec/shotengai/models_spec.rb[1:1:2:1]   | failed | 0.16917 seconds |
-./spec/shotengai/models_spec.rb[1:1:2:2]   | failed | 0.1559 seconds  |
-./spec/shotengai/models_spec.rb[1:1:2:3]   | failed | 0.16818 seconds |
-./spec/shotengai/models_spec.rb[1:1:3:1]   | failed | 0.17072 seconds |
-./spec/shotengai/models_spec.rb[1:1:3:2]   | failed | 0.17477 seconds |
-./spec/shotengai/models_spec.rb[1:1:3:3]   | failed | 0.16544 seconds |
-./spec/shotengai/models_spec.rb[1:1:4:1]   | failed | 0.1618 seconds  |
-./spec/shotengai/models_spec.rb[1:1:5:1]   | failed | 0.15564 seconds |
-./spec/shotengai/models_spec.rb[1:1:5:2:1] | failed | 0.15182 seconds |
-./spec/shotengai/models_spec.rb[1:1:5:2:2] | failed | 0.16236 seconds |
-./spec/shotengai/models_spec.rb[1:2:1:1]   | failed | 0.17459 seconds |
-./spec/shotengai/models_spec.rb[1:2:1:2]   | failed | 0.18331 seconds |
-./spec/shotengai/models_spec.rb[1:2:2:1]   | passed | 0.61428 seconds |
-./spec/shotengai/models_spec.rb[1:2:2:2]   | failed | 0.15561 seconds |
+./spec/shotengai/models_spec.rb[1:1:1:1]   | passed | 0.44582 seconds |
+./spec/shotengai/models_spec.rb[1:1:1:2]   | passed | 0.20555 seconds |
+./spec/shotengai/models_spec.rb[1:1:2:1]   | passed | 0.20124 seconds |
+./spec/shotengai/models_spec.rb[1:1:2:2]   | passed | 0.17955 seconds |
+./spec/shotengai/models_spec.rb[1:1:2:3]   | passed | 0.17157 seconds |
+./spec/shotengai/models_spec.rb[1:1:3:1]   | passed | 0.19801 seconds |
+./spec/shotengai/models_spec.rb[1:1:3:2]   | passed | 0.18172 seconds |
+./spec/shotengai/models_spec.rb[1:1:3:3]   | passed | 0.17998 seconds |
+./spec/shotengai/models_spec.rb[1:1:4:1]   | passed | 0.23986 seconds |
+./spec/shotengai/models_spec.rb[1:1:5:1]   | passed | 0.17938 seconds |
+./spec/shotengai/models_spec.rb[1:1:5:2:1] | passed | 0.24027 seconds |
+./spec/shotengai/models_spec.rb[1:1:5:2:2] | passed | 0.21941 seconds |
+./spec/shotengai/models_spec.rb[1:2:1:1]   | passed | 0.20203 seconds |
+./spec/shotengai/models_spec.rb[1:2:1:2]   | passed | 0.21369 seconds |
+./spec/shotengai/models_spec.rb[1:2:2:1]   | passed | 0.43436 seconds |
+./spec/shotengai/models_spec.rb[1:2:2:2]   | passed | 0.28966 seconds |

lib/shotengai/buyer.rb

@@ -7,7 +7,7 @@ module Shotengai
 
     class_methods do
       def can_shopping_with klass_name, options={}
-        klass = Object.const_get(klass_name)
+        klass = klass_name.constantize
         unless Shotengai::Order <=> klass # 为子类
           raise ArgumentError.new('You can only buy the class inherit from Shotengai::Order') 
         end

lib/shotengai/order.rb

@@ -84,7 +84,7 @@ module Shotengai
       end
 
       def can_buy *good_class_names
-        good_classes = good_class_names.map { |name| Object.const_get(name) }
+        good_classes = good_class_names.map(&:constantize)
         # 所有snapshot
         has_many :snapshots, -> { 
             where(type: good_classes.map { |good_class| "#{good_class.name}Snapshot" }) 

lib/shotengai/product.rb

@@ -53,8 +53,8 @@ module Shotengai
           class ::#{subclass}Snapshot < Shotengai::Snapshot; end
         ")
         subclass.instance_eval do
-          def series_class;  Object.const_get "#{self.name}Series" ; end
-          def snapshot_class; Object.const_get "#{self.name}Snapshot"; end
+          def series_class;  "#{self.name}Series".constantize ; end
+          def snapshot_class; "#{self.name}Snapshot".constantize; end
         end
       end
 

spec/shotengai/models_spec.rb

@@ -15,7 +15,6 @@ c.exec_update('drop database if exists shotengai_test;')
 c.exec_update('create database shotengai_test')
 c.exec_update('use shotengai_test')
 
-# 如何通过activerecord 建database
 RSpec.describe 'Shotengai Models' do
   before do
     ActiveRecord::Migration[5.1].subclasses.each do |migrate|

spec/spec_helper.rb

 require "bundler/setup"
 require 'rails'
+require 'active_record'
 require 'shotengai'
 require 'support/factory_girl'
 # Dir['../support/**/*.rb'].each { |f| require f }