load GeneralSettingsHelper#all_units from WeightsAndMeasures::UNITS

app/helpers/spree/admin/general_settings_helper.rb

@@ -5,11 +5,9 @@ module Spree
     module GeneralSettingsHelper
       def all_units
         [
-          "mg", "g", "kg", "T",
-          "oz", "lb",
-          "mL", "cL", "dL", "L", "kL",
-          "gal"
-        ]
+          WeightsAndMeasures::UNITS['weight'].values.pluck('name'),
+          WeightsAndMeasures::UNITS['volume'].values.pluck('name')
+        ].flatten.uniq
       end
     end
   end

spec/helpers/spree/admin/general_settings_helper_spec.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Spree::Admin::GeneralSettingsHelper, type: :helper do
+  describe "#all_units" do
+    it "returns all units" do
+      expect(helper.all_units).to eq(["mg", "g", "kg", "T", "oz", "lb", "mL", "cL", "dL", "L",
+                                      "kL", "gal"])
+    end
+  end
+end

spec/services/weights_and_measures_spec.rb

@@ -90,12 +90,4 @@ describe WeightsAndMeasures do
       end
     end
   end
-
-  describe "UNITS" do
-    include Spree::Admin::GeneralSettingsHelper
-    it "should include all the available untis" do
-      units = WeightsAndMeasures::UNITS.values.flat_map(&:values).pluck("name").sort.uniq
-      expect(units).to eq(all_units.sort.uniq)
-    end
-  end
 end