feat: adds smartrate functionality (#117)

* feat: adds smartrate functionality

* better smartrate test assertions

* fix: do not use refresh_from on get_smartrates

* fix: strip result key from smartrate response

* digs for smartrate result key

* fix: add empty array fallback to smartrate

lib/easypost/shipment.rb

@@ -6,6 +6,12 @@ def get_rates(params={})
     return self
   end
 
+  def get_smartrates
+    response = EasyPost.make_request(:get, url + '/smartrate', @api_key)
+
+    return response.fetch('result', [])
+  end
+
   def buy(params={})
     if params.instance_of?(EasyPost::Rate)
       temp = params.clone

spec/shipment_spec.rb

@@ -151,4 +151,25 @@
       expect(shipment.id).not_to eq(tracking_code)
     end
   end
+
+  describe '#smartrate' do
+    it 'retrieves the smartrates for a shipment' do
+      shipment = EasyPost::Shipment.create(
+        :to_address => ADDRESS[:missouri],
+        :from_address => ADDRESS[:california],
+        :parcel => PARCEL[:dimensions]
+      )
+      expect(shipment.rates).not_to be nil
+
+      smartrates = shipment.get_smartrates
+      expect(shipment.rates[0]['id']).to eq(smartrates[0]['id'])
+      expect(smartrates[0]['time_in_transit']['percentile_50']).to eq(1)
+      expect(smartrates[0]['time_in_transit']['percentile_75']).to eq(2)
+      expect(smartrates[0]['time_in_transit']['percentile_85']).to eq(2)
+      expect(smartrates[0]['time_in_transit']['percentile_90']).to eq(3)
+      expect(smartrates[0]['time_in_transit']['percentile_95']).to eq(3)
+      expect(smartrates[0]['time_in_transit']['percentile_97']).to eq(4)
+      expect(smartrates[0]['time_in_transit']['percentile_99']).to eq(5)
+    end
+  end
 end