Add spec for shipping categories

spec/controllers/spree/admin/shipping_categories_controller_spec.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+module Spree
+  module Admin
+    describe ShippingCategoriesController, type: :controller do
+      include AuthenticationWorkflow
+
+      describe "#create and #update" do
+        before { login_as_admin }
+
+        it "creates a shipping shipping category" do
+          expect {
+            spree_post :create, shipping_category: { name: "Frozen" }
+          }.to change(Spree::ShippingCategory.all, :count).by(1)
+
+          expect(response).to redirect_to spree.admin_shipping_categories_url
+        end
+
+        it "updates an existing shipping category" do
+          shipping_category = create(:shipping_category)
+          spree_put :update, id: shipping_category.id,
+                             shipping_category: { name: "Super Frozen" }
+
+          expect(response).to redirect_to spree.admin_shipping_categories_url
+          expect(shipping_category.reload.name).to eq "Super Frozen"
+        end
+      end
+    end
+  end
+end