Fix #4172 donation validation display error

Gemfile.lock

@@ -787,4 +787,4 @@ DEPENDENCIES
   webmock (~> 3.23)
 
 BUNDLED WITH
-   2.5.11
+   2.5.14

app/controllers/donations_controller.rb

@@ -84,7 +84,7 @@ def update
     redirect_to donations_path
   rescue => e
     flash[:alert] = "Error updating donation: #{e.message}"
-    render "edit"
+    redirect_back(fallback_location: edit_donation_path)
   end
 
   def destroy

spec/controllers/donations_controller_spec.rb

@@ -119,7 +119,7 @@
           }
           donation_params = { source: donation.source, storage_location: new_storage_location, line_items_attributes: line_item_params }
           put :update, params: { id: donation.id, donation: donation_params }
-          expect(response).not_to redirect_to(anything)
+          expect(response).to redirect_to(edit_donation_path(donation))
           expect(original_storage_location.size).to eq 5
           expect(new_storage_location.size).to eq 0
           expect(donation.reload.line_items.first.quantity).to eq 10

spec/requests/donations_requests_spec.rb

@@ -172,5 +172,47 @@
         expect(response.body).to_not include("you’ll need to make an adjustment to the inventory as well.")
       end
     end
+
+    # Bug fix - Issue #4172
+    context "when donated items are distributed to less than donated amount " \
+    "and you edit the donation to less than distributed amount" do
+      it "shows a warning and displays original names and amounts" do
+        item = create(:item, organization: organization, name: "Brightbloom Seed")
+        storage_location = create(:storage_location, :with_items, item: item, item_quantity: 0, organization: organization)
+        original_quantity = 100
+        donation = create(:donation, :with_items, item: item, item_quantity: original_quantity, organization: organization, storage_location: storage_location)
+        distribution = {
+          storage_location_id: storage_location.id,
+          partner_id: create(:partner).id,
+          delivery_method: :delivery,
+          line_items_attributes: {
+            "0": { item_id: item.id, quantity: 90 }
+          }
+        }
+
+        post distributions_path(distribution: distribution, format: :turbo_stream)
+
+        edited_donation = {
+          storage_location_id: storage_location.id,
+          line_items_attributes: {
+            "0": { item_id: item.id, quantity: 1 }
+          }
+        }
+        put donation_path(id: donation.id, donation: edited_donation)
+
+        expect(response).to redirect_to(edit_donation_path(donation))
+
+        get response.headers['Location']
+
+        if Event.read_events?(organization)
+          expect(flash[:alert]).to include("Error updating donation: Could not reduce quantity by 99 - current quantity is 10 for Brightbloom Seed")
+        else # TODO remove this branch when switching to events
+          expect(flash[:alert]).to include("Error updating donation: Requested items exceed the available inventory")
+        end
+
+        expect(response.body).to include(item.name)
+        expect(response.body).to include(original_quantity.to_s)
+      end
+    end
   end
 end