fix existing tests

app/services/weights_and_measures.rb

@@ -46,7 +46,7 @@ class WeightsAndMeasures
   }.freeze
 
   def scales_for_variant_unit
-    @scales_for_variant_unit ||= @units[@variant.product.variant_unit].reject { |_scale, unit_info|
+    @scales_for_variant_unit ||= @units[@variant.product.variant_unit]&.reject { |_scale, unit_info|
       available_units.exclude?(unit_info['name'])
     }
   end

spec/models/spree/line_item_spec.rb

@@ -695,6 +695,13 @@ module Spree
         let(:p2) { create(:product, name: 'Clear United States Honey', variant_unit_scale: 453.6) }
         let(:v2) { create(:variant, product: p2, unit_value: 453.6) }
         let(:li2) { create(:line_item, order: o, product: p2, variant: v2) }
+        let(:available_units) {
+          ["mg", "g", "kg", "T", "oz", "lb", "mL", "cL", "dL", "L", "kL", "gal"].join(",")
+        }
+
+        before do
+          Spree::Config.set_preference(:available_units, available_units)
+        end
 
         it "returns options_text" do
           li = build_stubbed(:line_item)

spec/services/unit_prices_spec.rb

@@ -6,9 +6,13 @@ describe UnitPrice do
   subject { UnitPrice.new(variant) }
   let(:variant) { Spree::Variant.new }
   let(:product) { instance_double(Spree::Product) }
+  let(:available_units) {
+    ["mg", "g", "kg", "T", "oz", "lb", "mL", "cL", "dL", "L", "kL", "gal"].join(",")
+  }
 
   before do
     allow(variant).to receive(:product) { product }
+    Spree::Config.set_preference(:available_units, available_units)
   end
 
   describe "#unit" do

spec/services/variant_units/option_value_namer_spec.rb

@@ -4,6 +4,13 @@ require 'spec_helper'
 
 module VariantUnits
   describe OptionValueNamer do
+    let(:available_units) {
+      ["mg", "g", "kg", "T", "oz", "lb", "mL", "cL", "dL", "L", "kL", "gal"].join(",")
+    }
+
+    before do
+      Spree::Config.set_preference(:available_units, available_units)
+    end
     describe "generating option value name" do
       let(:v) { Spree::Variant.new }
       let(:p) { Spree::Product.new }

spec/services/weights_and_measures_spec.rb

@@ -6,9 +6,13 @@ describe WeightsAndMeasures do
   subject { WeightsAndMeasures.new(variant) }
   let(:variant) { Spree::Variant.new }
   let(:product) { instance_double(Spree::Product) }
+  let(:available_units) {
+    ["mg", "g", "kg", "T", "oz", "lb", "mL", "cL", "dL", "L", "kL", "gal"].join(",")
+  }
 
   before do
     allow(variant).to receive(:product) { product }
+    Spree::Config.set_preference(:available_units, available_units)
   end
 
   describe "#system" do
@@ -69,16 +73,43 @@ describe WeightsAndMeasures do
           allow(variant).to receive(:unit_value) { 1500 }
           expect(subject.scale_for_unit_value).to eq([1000.0, "kg"])
         end
+
+        describe "should not display in kg if this unit is not selected" do
+          let(:available_units) { ["mg", "g", "T"].join(",") }
+
+          it "should display in g" do
+            allow(product).to receive(:variant_unit_scale) { 1.0 }
+            allow(variant).to receive(:unit_value) { 1500 }
+            expect(subject.scale_for_unit_value).to eq([1.0, "g"])
+          end
+        end
       end
     end
 
     context "volume" do
-      it "for a unit value that should display in L" do
+      it "for a unit value that should display in kL" do
         allow(product).to receive(:variant_unit) { "volume" }
         allow(product).to receive(:variant_unit_scale) { 1.0 }
         allow(variant).to receive(:unit_value) { 1500 }
         expect(subject.scale_for_unit_value).to eq([1000, "kL"])
       end
+
+      it "for a unit value that should display in dL" do
+        allow(product).to receive(:variant_unit) { "volume" }
+        allow(product).to receive(:variant_unit_scale) { 1.0 }
+        allow(variant).to receive(:unit_value) { 0.5 }
+        expect(subject.scale_for_unit_value).to eq([0.1, "dL"])
+      end
+
+      context "should not display in dL/cL if those units are not selected" do
+        let(:available_units){ ["mL", "L", "kL", "gal"].join(",") }
+        it "for a unit value that should display in mL" do
+          allow(product).to receive(:variant_unit) { "volume" }
+          allow(product).to receive(:variant_unit_scale) { 1.0 }
+          allow(variant).to receive(:unit_value) { 0.5 }
+          expect(subject.scale_for_unit_value).to eq([0.001, "mL"])
+        end
+      end
     end
 
     context "items" do

spec/system/admin/product_import_spec.rb

@@ -53,6 +53,14 @@ describe "Product Import" do
 
   let(:shipping_category_id_str) { Spree::ShippingCategory.all.first.id.to_s }
 
+  let(:available_units) {
+    ["mg", "g", "kg", "T", "oz", "lb", "mL", "cL", "dL", "L", "kL", "gal"].join(",")
+  }
+
+  before do
+    Spree::Config.set_preference(:available_units, available_units)
+  end
+
   describe "when importing products from uploaded file" do
     before do
       allow(Spree::Config).to receive(:available_units).and_return("g,lb,oz,kg,T,mL,L,kL")