diff --git a/core/app/models/spree/stock_movement.rb b/core/app/models/spree/stock_movement.rb
index baac5229050..b2fcb79a581 100644
--- a/core/app/models/spree/stock_movement.rb
+++ b/core/app/models/spree/stock_movement.rb
@@ -1,5 +1,10 @@
 module Spree
   class StockMovement < Spree::Base
+    QUANTITY_LIMITS = {
+      max: 2**31 - 1,
+      min: -2**31
+    }.freeze
+
     belongs_to :stock_item, class_name: 'Spree::StockItem', inverse_of: :stock_movements
     belongs_to :originator, polymorphic: true
 
@@ -8,11 +13,11 @@ class StockMovement < Spree::Base
     with_options presence: true do
       validates :stock_item
       validates :quantity, numericality: {
-                                            greater_than_or_equal_to: -2**31,
-                                            less_than_or_equal_to: 2**31 - 1,
-                                            only_integer: true,
-                                            allow_nil: true
-                                          }
+        greater_than_or_equal_to: QUANTITY_LIMITS[:min],
+        less_than_or_equal_to: QUANTITY_LIMITS[:max],
+        only_integer: true,
+        allow_nil: true
+      }
     end
 
     scope :recent, -> { order(created_at: :desc) }
@@ -20,7 +25,7 @@ class StockMovement < Spree::Base
     self.whitelisted_ransackable_attributes = ['quantity']
 
     def readonly?
-      !new_record?
+      persisted?
     end
 
     private
diff --git a/core/spec/models/spree/stock_movement_spec.rb b/core/spec/models/spree/stock_movement_spec.rb
index 33a178651b3..5abc7242f6c 100644
--- a/core/spec/models/spree/stock_movement_spec.rb
+++ b/core/spec/models/spree/stock_movement_spec.rb
@@ -1,55 +1,119 @@
 require 'spec_helper'
 
 describe Spree::StockMovement, :type => :model do
-  let(:stock_location) { create(:stock_location_with_items) }
-  let(:stock_item) { stock_location.stock_items.order(:id).first }
-  subject { build(:stock_movement, stock_item: stock_item) }
 
-  it 'should belong to a stock item' do
-    expect(subject).to respond_to(:stock_item)
+  describe 'Constants' do
+    describe 'QUANTITY_LIMITS[:max]' do
+      it 'return 2**31 - 1' do
+        expect(Spree::StockMovement::QUANTITY_LIMITS[:max]).to eq(2**31 - 1)
+      end
+    end
+
+    describe 'QUANTITY_LIMITS[:min]' do
+      it 'return -2**31' do
+        expect(Spree::StockMovement::QUANTITY_LIMITS[:min]).to eq(-2**31)
+      end
+    end
   end
 
-  it 'is readonly unless new' do
-    subject.save
-    expect {
-      subject.save
-    }.to raise_error(ActiveRecord::ReadOnlyRecord)
+  describe 'Associations' do
+    it { is_expected.to belong_to(:stock_item).class_name('Spree::StockItem').inverse_of(:stock_movements) }
+    it { is_expected.to belong_to(:originator) }
   end
 
-  it 'does not update count on hand when track inventory levels is false' do
-    Spree::Config[:track_inventory_levels] = false
-    subject.quantity = 1
-    subject.save
-    stock_item.reload
-    expect(stock_item.count_on_hand).to eq(10)
+  describe 'Validations' do
+    it do
+      is_expected.to validate_presence_of(:stock_item)
+    end
+
+    it do
+      is_expected.to validate_presence_of(:quantity)
+    end
+
+    it do
+      is_expected.to validate_numericality_of(:quantity).
+        is_greater_than_or_equal_to(Spree::StockMovement::QUANTITY_LIMITS[:min]).
+        is_less_than_or_equal_to(Spree::StockMovement::QUANTITY_LIMITS[:max]).only_integer.allow_nil
+    end
   end
 
-  it 'does not update count on hand when variant inventory tracking is off' do
-    stock_item.variant.track_inventory = false
-    subject.quantity = 1
-    subject.save
-    stock_item.reload
-    expect(stock_item.count_on_hand).to eq(10)
+  describe 'Callbacks' do
+    it { is_expected.to callback(:update_stock_item_quantity).after(:create) }
   end
 
-  context "when quantity is negative" do
-    context "after save" do
-      it "should decrement the stock item count on hand" do
-        subject.quantity = -1
-        subject.save
-        stock_item.reload
-        expect(stock_item.count_on_hand).to eq(9)
+  describe 'Scope' do
+    describe '.recent' do
+      it 'should order chronologically by created at' do
+        expect(Spree::StockMovement.recent.to_sql).
+          to eq Spree::StockMovement.unscoped.order(created_at: :desc).to_sql
       end
     end
   end
 
-  context "when quantity is positive" do
-    context "after save" do
-      it "should increment the stock item count on hand" do
-        subject.quantity = 1
-        subject.save
-        stock_item.reload
-        expect(stock_item.count_on_hand).to eq(11)
+  describe 'whitelisted ransackable attributes' do
+    it 'returns amount attribute' do
+      expect(Spree::StockMovement.whitelisted_ransackable_attributes).to eq(['quantity'])
+    end
+  end
+
+  describe 'Insatance Methods' do
+    let(:stock_location) { create(:stock_location_with_items) }
+    let(:stock_item) { stock_location.stock_items.order(:id).first }
+
+    describe '#readonly?' do
+      let(:stock_movement) { create(:stock_movement, stock_item: stock_item) }
+      it 'should not update a persisted record' do
+        expect { stock_movement.save }.to raise_error(ActiveRecord::ReadOnlyRecord)
+      end
+    end
+
+    describe '#update_stock_item_quantity' do
+      let(:stock_movement) { build(:stock_movement, stock_item: stock_item) }
+
+      context 'when track inventory levels is false' do
+        before do
+          Spree::Config[:track_inventory_levels] = false
+          stock_movement.quantity = 1
+          stock_movement.save
+          stock_item.reload
+        end
+        it 'does not update count on hand' do
+          expect(stock_item.count_on_hand).to eq(10)
+        end
+      end
+
+      context 'when track inventory tracking is off' do
+        before do
+          stock_item.variant.track_inventory = false
+          stock_movement.quantity = 1
+          stock_movement.save
+          stock_item.reload
+        end
+        it 'does not update count on hand' do
+          expect(stock_item.count_on_hand).to eq(10)
+        end
+      end
+
+      context 'when quantity is negative' do
+        before do
+          stock_movement.quantity = -1
+          stock_movement.save
+          stock_item.reload
+        end
+        it 'should decrement the stock item count on hand' do
+          expect(stock_item.count_on_hand).to eq(9)
+        end
+      end
+
+      context "when quantity is positive" do
+        before do
+          stock_movement.quantity = 1
+          stock_movement.save
+          stock_item.reload
+        end
+        it "should increment the stock item count on hand" do
+          expect(stock_item.count_on_hand).to eq(11)
+        end
       end
     end
   end