Do not mutate config's state in specs

spec/models/spree/adjustment_spec.rb

@@ -75,17 +75,19 @@ module Spree
         end
 
         describe "when tax on shipping is disabled" do
-          before { Config.shipment_inc_vat = false }
+          before do
+            allow(Config).to receive(:shipment_inc_vat).and_return(false)
+          end
 
           it "records 0% tax on shipment adjustments" do
-            Config.shipping_tax_rate = 0
+            allow(Config).to receive(:shipping_tax_rate).and_return(0)
             order.shipments = [shipment]
 
             expect(order.adjustments.first.included_tax).to eq(0)
           end
 
           it "records 0% tax on shipments when a rate is set but shipment_inc_vat is false" do
-            Config.shipping_tax_rate = 0.25
+            allow(Config).to receive(:shipping_tax_rate).and_return(0.25)
             order.shipments = [shipment]
 
             expect(order.adjustments.first.included_tax).to eq(0)
@@ -93,10 +95,12 @@ module Spree
         end
 
         describe "when tax on shipping is enabled" do
-        before { Config.shipment_inc_vat = true }
+          before do
+            allow(Config).to receive(:shipment_inc_vat).and_return(true)
+          end
 
           it "takes the shipment adjustment tax included from the system setting" do
-            Config.shipping_tax_rate = 0.25
+            allow(Config).to receive(:shipping_tax_rate).and_return(0.25)
             order.shipments = [shipment]
 
             # Finding the tax included in an amount that's already inclusive of tax:
@@ -107,7 +111,7 @@ module Spree
           end
 
           it "records 0% tax on shipments when shipping_tax_rate is not set" do
-            Config.shipping_tax_rate = nil
+            allow(Config).to receive(:shipping_tax_rate).and_return(0)
             order.shipments = [shipment]
 
             expect(order.adjustments.first.included_tax).to eq(0)

spec/models/spree/order_spec.rb

@@ -229,8 +229,8 @@ describe Spree::Order do
 
     context "with a taxed shipment" do
       before do
-        Spree::Config.shipment_inc_vat = true
-        Spree::Config.shipping_tax_rate = 0.25
+        allow(Spree::Config).to receive(:shipment_inc_vat).and_return(true)
+        allow(Spree::Config).to receive(:shipping_tax_rate).and_return(0.25)
       end
 
       let!(:shipment) { create(:shipment_with, :shipping_method, shipping_method: shipping_method, order: order) }
@@ -261,8 +261,8 @@ describe Spree::Order do
 
   describe "getting the total tax" do
     before do
-      Spree::Config.shipment_inc_vat = true
-      Spree::Config.shipping_tax_rate = 0.25
+      allow(Spree::Config).to receive(:shipment_inc_vat).and_return(true)
+      allow(Spree::Config).to receive(:shipping_tax_rate).and_return(0.25)
     end
 
     let(:order) { create(:order) }
@@ -321,8 +321,8 @@ describe Spree::Order do
     end
 
     before do
-      Spree::Config.shipment_inc_vat = true
-      Spree::Config.shipping_tax_rate = tax_rate15.amount
+      allow(Spree::Config).to receive(:shipment_inc_vat).and_return(true)
+      allow(Spree::Config).to receive(:shipping_tax_rate).and_return(tax_rate15.amount)
     end
 
     let(:shipping_method) { create(:shipping_method, calculator: Spree::Calculator::FlatRate.new(preferred_amount: 46.0)) }