From 2a0f132b8b641ab1d18632e485f717b24cc435bd Mon Sep 17 00:00:00 2001
From: Matt-Yorkley <9029026+Matt-Yorkley@users.noreply.github.com>
Date: Tue, 8 Dec 2020 18:32:22 +0000
Subject: [PATCH] Improve ShippingMethod -> Shipment association

https://github.com/spree/spree/commit/5a54a0b6b0abc9ea3b928a243c2daace9a36c1b1
---
 app/models/spree/shipping_method.rb       |  2 +-
 spec/models/spree/shipping_method_spec.rb | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/app/models/spree/shipping_method.rb b/app/models/spree/shipping_method.rb
index fd7b1e4415..38f8a41438 100644
--- a/app/models/spree/shipping_method.rb
+++ b/app/models/spree/shipping_method.rb
@@ -10,7 +10,7 @@ module Spree
 
     default_scope -> { where(deleted_at: nil) }
 
-    has_many :shipments
+    has_many :shipments, through: :shipping_rates
     has_many :shipping_method_categories
     has_many :shipping_categories, through: :shipping_method_categories
     has_many :shipping_rates, inverse_of: :shipping_method
diff --git a/spec/models/spree/shipping_method_spec.rb b/spec/models/spree/shipping_method_spec.rb
index 35ecfa6d83..c3c65d0215 100644
--- a/spec/models/spree/shipping_method_spec.rb
+++ b/spec/models/spree/shipping_method_spec.rb
@@ -176,5 +176,19 @@ module Spree
         expect(shipping_method.calculator.calculable).to eq(shipping_method)
       end
     end
+
+    # Regression test for Spree #4492
+    context "#shipments" do
+      let!(:shipping_method) { create(:shipping_method) }
+      let!(:shipment) do
+        shipment = create(:shipment)
+        shipment.shipping_rates.create!(shipping_method: shipping_method)
+        shipment
+      end
+
+      it "can gather all the related shipments" do
+        expect(shipping_method.shipments).to include(shipment)
+      end
+    end
   end
 end