use arel_table in Promotion.with_coupon_code and Promotion.coupons

core/app/models/spree/promotion.rb

@@ -27,7 +27,8 @@ class Promotion < Spree::Base
 
     before_save :normalize_blank_values
 
-    scope :coupons, -> { where("#{table_name}.code IS NOT NULL") }
+    scope :coupons, -> { where(arel_table[:code].not_eq(nil)) }
+
     scope :applied, lambda {
       joins(<<-SQL).uniq
         INNER JOIN spree_order_promotions
@@ -39,7 +40,7 @@ class Promotion < Spree::Base
     self.whitelisted_ransackable_attributes = ['path', 'promotion_category_id', 'code']
 
     def self.with_coupon_code(coupon_code)
-      where("lower(#{table_name}.code) = ?", coupon_code.strip.downcase).first
+      where(arel_table[:code].lower.eq(coupon_code.strip.downcase)).first
     end
 
     def self.active

core/spec/models/spree/promotion_spec.rb

@@ -57,6 +57,16 @@
     end
   end
 
+  # Regression test for #4081
+  describe ".with_coupon_code" do
+    context "and code stored in uppercase" do
+      let!(:promotion) { create(:promotion, :code => "MY-COUPON-123") }
+      it "finds the code with lowercase" do
+        expect(Spree::Promotion.with_coupon_code("my-coupon-123")).to eql promotion
+      end
+    end
+  end
+
   describe "#destroy" do
     let(:promotion) { Spree::Promotion.create(:name => "delete me") }
 
@@ -515,16 +525,6 @@
     end
   end
 
-  # Regression test for #4081
-  describe "#with_coupon_code" do
-    context "and code stored in uppercase" do
-      let!(:promotion) { create(:promotion, :code => "MY-COUPON-123") }
-      it "finds the code with lowercase" do
-        expect(Spree::Promotion.with_coupon_code("my-coupon-123")).to eql promotion
-      end
-    end
-  end
-
   describe '#used_by?' do
     subject { promotion.used_by? user, [excluded_order] }