diff --git a/spec/services/order_invoice_comparator_spec.rb b/spec/services/order_invoice_comparator_spec.rb
index 778bd769ae..6ee0fa7341 100644
--- a/spec/services/order_invoice_comparator_spec.rb
+++ b/spec/services/order_invoice_comparator_spec.rb
@@ -4,7 +4,8 @@ require 'spec_helper'
 
 describe OrderInvoiceComparator do
   describe '#can_generate_new_invoice?' do
-    let!(:order) { create(:completed_order_with_fees) }
+    # this passes 'order' as argument to the invoice comparator
+    let(:order) { create(:completed_order_with_fees) }
     let!(:invoice_data_generator){ InvoiceDataGenerator.new(order) }
     let!(:invoice){
       create(:invoice,
@@ -16,19 +17,101 @@ describe OrderInvoiceComparator do
     }
 
     context "changes on the order object" do
-      it "returns true if the order didn't change" do
-        expect(subject).to be false
+      describe "detecting relevant attribute changes" do
+        it "returns true if a relevant attribute changes" do
+          Spree::Order.where(id: order.id).update_all(payment_total: order.payment_total + 10)
+          order.reload
+          expect(subject).to be true
+        end
+
+        it "returns true if a relevant attribute changes" do
+          Spree::Order.where(id: order.id).update_all(total: order.total + 10)
+          order.reload
+          expect(subject).to be true
+        end
+
+        it "returns true if a relevant attribute changes - order state: cancelled" do
+          order.cancel!
+          expect(subject).to be true
+        end
+
+        it "returns true if a relevant attribute changes - order state: resumed" do
+          order.cancel!
+          order.resume!
+          expect(subject).to be true
+        end
+
+        context "additional tax total changes" do
+          let(:order) do
+            create(:order_with_taxes, product_price: 110, tax_rate_amount: 0.1,
+                                      included_in_price: false)
+              .tap do |order|
+              order.create_tax_charge!
+              order.update_shipping_fees!
+            end
+          end
+
+          it "returns returns true" do
+            Spree::TaxRate.first.update!(amount: 0.15)
+            order.create_tax_charge!
+            order.reload
+            expect(subject).to be true
+          end
+        end
+
+        context "included tax total changes" do
+          let(:order) do
+            create(:order_with_taxes, product_price: 110, tax_rate_amount: 0.1,
+                                      included_in_price: true)
+              .tap do |order|
+              order.create_tax_charge!
+              order.update_shipping_fees!
+            end
+          end
+
+          it "returns returns true" do
+            Spree::TaxRate.first.update!(amount: 0.15)
+            order.create_tax_charge!
+            order.reload
+            expect(subject).to be true
+          end
+        end
+
+        context "shipping method changes" do
+          let(:shipping_method) { create(:shipping_method) }
+          it "returns returns true" do
+            Spree::ShippingRate.first.update(shipping_method_id: shipping_method.id)
+            expect(subject).to be true
+          end
+        end
       end
 
-      it "returns true if a relevant attribute changes" do
-        Spree::Order.where(id: order.id).update_all(payment_total: order.payment_total + 10)
-        order.reload
-        expect(subject).to be true
-      end
+      describe "ignoring non-relevant attribute changes" do
+        it "returns false if the order didn't change" do
+          expect(subject).to be false
+        end
 
-      it "returns true if a non-relevant attribute changes" do
-        order.update!(note: "THIS IS A NEW NOTE")
-        expect(subject).to be false
+        it "returns false if an attribute which should not change, changes" do
+          Spree::Order.where(id: order.id).update_all(number: 'R631504404')
+          order.reload
+          expect(subject).to be false
+        end
+
+        it "returns false if an attribute which should not change, changes" do
+          Spree::Order.where(id: order.id).update_all(currency: 'EUR')
+          order.reload
+          expect(subject).to be false
+        end
+
+        it "returns false if a non-relevant attribute changes" do
+          order.update!(special_instructions: "A very special insctruction.")
+          expect(subject).to be false
+        end
+
+        it "returns false if a non-relevant attribute changes" do
+          order.update!(note: "THIS IS A NEW NOTE")
+          expect(subject).to be false
+        end
       end
     end