Use after_create callback to duplicate master variant

app/models/spree/product_decorator.rb

@@ -32,7 +32,7 @@ Spree::Product.class_eval do
   validates_presence_of :variant_unit_name,
                         if: -> p { p.variant_unit == 'items' }
 
-  after_initialize :ensure_first_standard_variant, :if => :new_record?
+  after_create :ensure_one_standard_variant
   after_initialize :set_available_on_to_now, :if => :new_record?
   after_save :update_units
   after_touch :touch_distributors
@@ -206,7 +206,10 @@ Spree::Product.class_eval do
     Spree::OptionType.where('name LIKE ?', 'unit_%%')
   end
 
-  def ensure_first_standard_variant
-    self.variants << Spree::Variant.new
+  def ensure_one_standard_variant
+    variant = self.master.dup
+    variant.product = self
+    variant.is_master = false
+    self.variants << variant
   end
 end

spec/models/spree/product_spec.rb

@@ -85,11 +85,21 @@ module Spree
           end
         end
 
-        context "instatiating a new product" do
-          let!(:product) { Spree::Product.new }
+        context "saving a new product" do
+          let!(:product){ Spree::Product.new }
 
-          it "creates a standard (non-master) variant when created" do
-            product.variants.should_not be_empty
+          before do
+            product.primary_taxon = create(:taxon)
+            product.supplier = create(:supplier_enterprise)
+            product.name = "Product1"
+            product.on_hand = 3
+            product.price = 4.27
+            product.save!
+          end
+
+          it "copies the properties on master variant to the first standard variant" do
+            standard_variant = product.variants(:reload).first
+            expect(standard_variant.price).to eq product.master.price
           end
         end