diff --git a/app/models/spree/shipment.rb b/app/models/spree/shipment.rb
index b49f8f5bdc..f3b0b03f0c 100644
--- a/app/models/spree/shipment.rb
+++ b/app/models/spree/shipment.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'ostruct'
 
 module Spree
@@ -28,7 +30,8 @@ module Spree
     scope :with_state, ->(*s) { where(state: s) }
     scope :trackable, -> { where("tracking IS NOT NULL AND tracking != ''") }
 
-    # shipment state machine (see http://github.com/pluginaweek/state_machine/tree/master for details)
+    # Shipment state machine
+    # See http://github.com/pluginaweek/state_machine/tree/master for details
     state_machine initial: :pending, use_transactions: false do
       event :ready do
         transition from: :pending, to: :ready, if: lambda { |shipment|
@@ -70,12 +73,13 @@ module Spree
     end
 
     def backordered?
-      inventory_units.any? { |inventory_unit| inventory_unit.backordered? }
+      inventory_units.any?(&:backordered?)
     end
 
     def shipped=(value)
       return unless value == '1' && shipped_at.nil?
-      self.shipped_at = Time.now
+
+      self.shipped_at = Time.zone.now
     end
 
     def shipping_method
@@ -97,7 +101,7 @@ module Spree
     def selected_shipping_rate_id=(id)
       shipping_rates.update_all(selected: false)
       shipping_rates.update(id, selected: true)
-      self.save!
+      save!
     end
 
     def refresh_rates
@@ -119,8 +123,9 @@ module Spree
       order ? order.currency : Spree::Config[:currency]
     end
 
-    # The adjustment amount associated with this shipment (if any.)  Returns only the first adjustment to match
-    # the shipment but there should never really be more than one.
+    # The adjustment amount associated with this shipment (if any)
+    #   Returns only the first adjustment to match the shipment
+    #   There should never really be more than one.
     def cost
       adjustment ? adjustment.amount : 0
     end
@@ -149,7 +154,7 @@ module Spree
       Spree::Money.new(total_cost, { currency: currency })
     end
 
-    def editable_by?(user)
+    def editable_by?(_user)
       !shipped?
     end
 
@@ -162,7 +167,7 @@ module Spree
     end
 
     def line_items
-      if order.complete? and Spree::Config[:track_inventory_levels]
+      if order.complete? && Spree::Config[:track_inventory_levels]
         order.line_items.select { |li| inventory_units.pluck(:variant_id).include?(li.variant_id) }
       else
         order.line_items
@@ -182,14 +187,15 @@ module Spree
       manifest.each { |item| manifest_unstock(item) }
     end
 
-    # Updates various aspects of the Shipment while bypassing any callbacks.  Note that this method takes an explicit reference to the
-    # Order object.  This is necessary because the association actually has a stale (and unsaved) copy of the Order and so it will not
-    # yield the correct results.
+    # Updates various aspects of the Shipment while bypassing any callbacks.
+    #   Note that this method takes an explicit reference to the Order object.
+    #   This is necessary because the association actually has a stale (and unsaved) copy of the
+    #     Order and so it will not yield the correct results.
     def update!(order)
       old_state = state
       new_state = determine_state(order)
       update_column :state, new_state
-      after_ship if new_state == 'shipped' and old_state != 'shipped'
+      after_ship if new_state == 'shipped' && old_state != 'shipped'
     end
 
     # Determines the appropriate +state+ according to the following logic:
@@ -200,8 +206,9 @@ module Spree
     def determine_state(order)
       return 'canceled' if order.canceled?
       return 'pending' unless order.can_ship?
-      return 'pending' if inventory_units.any? &:backordered?
+      return 'pending' if inventory_units.any?(&:backordered?)
       return 'shipped' if state == 'shipped'
+
       order.paid? ? 'ready' : 'pending'
     end
 
@@ -226,65 +233,72 @@ module Spree
     end
 
     def set_up_inventory(state, variant, order)
-      self.inventory_units.create(variant_id: variant.id, state: state, order_id: order.id)
+      inventory_units.create(variant_id: variant.id, state: state, order_id: order.id)
     end
 
     private
 
-      def manifest_unstock(item)
-        stock_location.unstock item.variant, item.quantity, self
-      end
+    def manifest_unstock(item)
+      stock_location.unstock item.variant, item.quantity, self
+    end
 
-      def manifest_restock(item)
-        stock_location.restock item.variant, item.quantity, self
-      end
+    def manifest_restock(item)
+      stock_location.restock item.variant, item.quantity, self
+    end
 
-      def generate_shipment_number
-        return number unless number.blank?
-        record = true
-        while record
-          random = "H#{Array.new(11) { rand(9) }.join}"
-          record = self.class.where(number: random).first
-        end
-        self.number = random
-      end
+    def generate_shipment_number
+      return number if number.present?
 
-      def description_for_shipping_charge
-        "#{Spree.t(:shipping)} (#{shipping_method.name})"
+      record = true
+      while record
+        random = "H#{Array.new(11) { rand(9) }.join}"
+        record = self.class.where(number: random).first
       end
+      self.number = random
+    end
 
-      def validate_shipping_method
-        unless shipping_method.nil?
-          errors.add :shipping_method, Spree.t(:is_not_available_to_shipment_address) unless shipping_method.include?(address)
-        end
-      end
+    def description_for_shipping_charge
+      "#{Spree.t(:shipping)} (#{shipping_method.name})"
+    end
 
-      def after_ship
-        inventory_units.each &:ship!
-        adjustment.finalize!
-        send_shipped_email
-        touch :shipped_at
-      end
+    def validate_shipping_method
+      return if shipping_method.nil?
 
-      def send_shipped_email
-        ShipmentMailer.shipped_email(self.id).deliver
-      end
+      return if shipping_method.include?(address)
 
-      def ensure_correct_adjustment
-        if adjustment
-          adjustment.originator = shipping_method
-          adjustment.label = shipping_method.adjustment_label
-          adjustment.amount = selected_shipping_rate.cost if adjustment.open?
-          adjustment.save!
-          adjustment.reload
-        elsif selected_shipping_rate_id
-          shipping_method.create_adjustment shipping_method.adjustment_label, order, self, true, "open"
-          reload #ensure adjustment is present on later saves
-        end
-      end
+      errors.add :shipping_method, Spree.t(:is_not_available_to_shipment_address)
+    end
 
-      def update_order
-        order.update!
+    def after_ship
+      inventory_units.each(&:ship!)
+      adjustment.finalize!
+      send_shipped_email
+      touch :shipped_at
+    end
+
+    def send_shipped_email
+      ShipmentMailer.shipped_email(id).deliver
+    end
+
+    def ensure_correct_adjustment
+      if adjustment
+        adjustment.originator = shipping_method
+        adjustment.label = shipping_method.adjustment_label
+        adjustment.amount = selected_shipping_rate.cost if adjustment.open?
+        adjustment.save!
+        adjustment.reload
+      elsif selected_shipping_rate_id
+        shipping_method.create_adjustment(shipping_method.adjustment_label,
+                                          order,
+                                          self,
+                                          true,
+                                          "open")
+        reload # ensure adjustment is present on later saves
       end
+    end
+
+    def update_order
+      order.update!
+    end
   end
 end
diff --git a/spec/models/spree/shipment_spec.rb b/spec/models/spree/shipment_spec.rb
index a9992c89c5..0c71a3ea58 100644
--- a/spec/models/spree/shipment_spec.rb
+++ b/spec/models/spree/shipment_spec.rb
@@ -1,11 +1,12 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 require 'benchmark'
 
 describe Spree::Shipment do
-  let(:order) { mock_model Spree::Order, backordered?: false,
-                                         canceled?: false,
-                                         can_ship?: true,
-                                         currency: 'USD' }
+  let(:order) {
+    create(:order, backordered?: false, canceled?: false, can_ship?: true, currency: 'USD')
+  }
   let(:shipping_method) { create(:shipping_method, name: "UPS") }
   let(:shipment) do
     shipment = Spree::Shipment.new order: order
@@ -19,41 +20,41 @@ describe Spree::Shipment do
 
   it 'is backordered if one if its inventory_units is backordered' do
     shipment.stub(inventory_units: [
-      mock_model(Spree::InventoryUnit, backordered?: false),
-      mock_model(Spree::InventoryUnit, backordered?: true)
-    ])
+                    create(:inventory_unit, backordered?: false),
+                    create(:inventory_unit, backordered?: true)
+                  ])
     shipment.should be_backordered
   end
 
   context "#cost" do
     it "should return the amount of any shipping charges that it originated" do
       shipment.stub_chain :adjustment, amount: 10
-      shipment.cost.should == 10
+      expect(shipment.cost).to eq 10
     end
 
     it "should return 0 if there are no relevant shipping adjustments" do
-      shipment.cost.should == 0
+      expect(shipment.cost).to eq 0
     end
   end
 
   context "display_cost" do
     it "retuns a Spree::Money" do
       shipment.stub(:cost) { 21.22 }
-      shipment.display_cost.should == Spree::Money.new(21.22)
+      expect(shipment.display_cost).to eq Spree::Money.new(21.22)
     end
   end
 
   context "display_item_cost" do
     it "retuns a Spree::Money" do
       shipment.stub(:item_cost) { 21.22 }
-      shipment.display_item_cost.should == Spree::Money.new(21.22)
+      expect(shipment.display_item_cost).to eq Spree::Money.new(21.22)
     end
   end
 
   context "display_total_cost" do
     it "retuns a Spree::Money" do
       shipment.stub(:total_cost) { 21.22 }
-      shipment.display_total_cost.should == Spree::Money.new(21.22)
+      expect(shipment.display_total_cost).to eq Spree::Money.new(21.22)
     end
   end
 
@@ -115,10 +116,12 @@ describe Spree::Shipment do
     let(:shipment) { create(:shipment) }
     let(:shipping_method1) { create(:shipping_method) }
     let(:shipping_method2) { create(:shipping_method) }
-    let(:shipping_rates) { [
-      Spree::ShippingRate.new(shipping_method: shipping_method1, cost: 10.00, selected: true),
-      Spree::ShippingRate.new(shipping_method: shipping_method2, cost: 20.00)
-    ] }
+    let(:shipping_rates) {
+      [
+        Spree::ShippingRate.new(shipping_method: shipping_method1, cost: 10.00, selected: true),
+        Spree::ShippingRate.new(shipping_method: shipping_method2, cost: 20.00)
+      ]
+    }
 
     it 'returns shipping_method from selected shipping_rate' do
       shipment.shipping_rates.delete_all
@@ -133,14 +136,14 @@ describe Spree::Shipment do
         Spree::Stock::Estimator.should_receive(:new).with(shipment.order).and_return(mock_estimator)
         shipment.stub(shipping_method: shipping_method2)
 
-        shipment.refresh_rates.should == shipping_rates
-        shipment.reload.selected_shipping_rate.shipping_method_id.should == shipping_method2.id
+        expect(shipment.refresh_rates).to eq shipping_rates
+        expect(shipment.reload.selected_shipping_rate.shipping_method_id).to eq shipping_method2.id
       end
 
       it 'should handle no shipping_method selection' do
         Spree::Stock::Estimator.should_receive(:new).with(shipment.order).and_return(mock_estimator)
         shipment.stub(shipping_method: nil)
-        shipment.refresh_rates.should == shipping_rates
+        expect(shipment.refresh_rates).to eq shipping_rates
         shipment.reload.selected_shipping_rate.should_not be_nil
       end
 
@@ -148,13 +151,16 @@ describe Spree::Shipment do
         Spree::Stock::Estimator.should_not_receive(:new)
         shipment.shipping_rates.delete_all
         shipment.stub(shipped?: true)
-        shipment.refresh_rates.should == []
+        expect(shipment.refresh_rates).to eq []
       end
 
       context 'to_package' do
         it 'should use symbols for states when adding contents to package' do
-          shipment.stub_chain(:inventory_units, includes: [ build(:inventory_unit, variant: variant, state: 'on_hand'),
-                                                            build(:inventory_unit, variant: variant, state: 'backordered') ] )
+          shipment.stub_chain(:inventory_units,
+                              includes: [build(:inventory_unit, variant: variant,
+                                                                state: 'on_hand'),
+                                         build(:inventory_unit, variant: variant,
+                                                                state: 'backordered')] )
           package = shipment.to_package
           package.on_hand.count.should eq 1
           package.backordered.count.should eq 1
@@ -245,7 +251,7 @@ describe Spree::Shipment do
       line_items = [mock_model(Spree::LineItem)]
       order.stub complete?: true
       order.stub line_items: line_items
-      shipment.line_items.should == line_items
+      expect(shipment.line_items).to eq line_items
     end
   end
 
@@ -287,7 +293,9 @@ describe Spree::Shipment do
     end
 
     it 'restocks the items' do
-      shipment.stub_chain(:inventory_units, :joins, includes: [mock_model(Spree::InventoryUnit, variant: variant)])
+      shipment.stub_chain(:inventory_units,
+                          :joins,
+                          includes: [mock_model(Spree::InventoryUnit, variant: variant)])
       shipment.stock_location = mock_model(Spree::StockLocation)
       shipment.stock_location.should_receive(:restock).with(variant, 1, shipment)
       shipment.after_cancel
@@ -307,7 +315,9 @@ describe Spree::Shipment do
     end
 
     it 'unstocks them items' do
-      shipment.stub_chain(:inventory_units, :joins, includes: [mock_model(Spree::InventoryUnit, variant: variant)])
+      shipment.stub_chain(:inventory_units,
+                          :joins,
+                          includes: [mock_model(Spree::InventoryUnit, variant: variant)])
       shipment.stock_location = mock_model(Spree::StockLocation)
       shipment.stock_location.should_receive(:unstock).with(variant, 1, shipment)
       shipment.after_resume
@@ -353,13 +363,13 @@ describe Spree::Shipment do
       }
       mail_message.should_receive :deliver
       shipment.ship!
-      shipment_id.should == shipment.id
+      expect(shipment_id).to eq shipment.id
     end
 
     it "should finalize the shipment's adjustment" do
       shipment.stub(:send_shipped_email)
       shipment.ship!
-      shipment.adjustment.state.should == 'finalized'
+      expect(shipment.adjustment.state).to eq 'finalized'
       shipment.adjustment.should be_immutable
     end
   end
@@ -376,17 +386,19 @@ describe Spree::Shipment do
     before { shipment.stub(:reload) }
 
     it "should create adjustment when not present" do
-      shipment.stub(:selected_shipping_rate_id => 1)
-      shipping_method.should_receive(:create_adjustment).with(shipping_method.adjustment_label, order, shipment, true, "open")
-      shipment.send(:ensure_correct_adjustment)
+      shipment.stub(selected_shipping_rate_id: 1)
+      shipping_method.should_receive(:create_adjustment).with(shipping_method.adjustment_label,
+                                                              order, shipment, true, "open")
+      shipment.__send__(:ensure_correct_adjustment)
     end
 
     # Regression test for #3138
     it "should use the shipping method's adjustment label" do
-      shipment.stub(:selected_shipping_rate_id => 1)
-      shipping_method.stub(:adjustment_label => "Foobar")
-      shipping_method.should_receive(:create_adjustment).with("Foobar", order, shipment, true, "open")
-      shipment.send(:ensure_correct_adjustment)
+      shipment.stub(selected_shipping_rate_id: 1)
+      shipping_method.stub(adjustment_label: "Foobar")
+      shipping_method.should_receive(:create_adjustment).with("Foobar", order,
+                                                              shipment, true, "open")
+      shipment.__send__(:ensure_correct_adjustment)
     end
 
     it "should update originator when adjustment is present" do
@@ -397,7 +409,7 @@ describe Spree::Shipment do
       shipment.adjustment.should_receive(:amount=).with(10.00)
       shipment.adjustment.should_receive(:save!)
       shipment.adjustment.should_receive(:reload)
-      shipment.send(:ensure_correct_adjustment)
+      shipment.__send__(:ensure_correct_adjustment)
     end
 
     it 'should not update amount if adjustment is not open?' do
@@ -408,14 +420,14 @@ describe Spree::Shipment do
       shipment.adjustment.should_not_receive(:amount=).with(10.00)
       shipment.adjustment.should_receive(:save!)
       shipment.adjustment.should_receive(:reload)
-      shipment.send(:ensure_correct_adjustment)
+      shipment.__send__(:ensure_correct_adjustment)
     end
   end
 
   context "update_order" do
     it "should update order" do
       order.should_receive(:update!)
-      shipment.send(:update_order)
+      shipment.__send__(:update_order)
     end
   end
 
@@ -429,7 +441,7 @@ describe Spree::Shipment do
 
   context "currency" do
     it "returns the order currency" do
-      shipment.currency.should == order.currency
+      expect(shipment.currency).to eq order.currency
     end
   end
 
@@ -438,7 +450,7 @@ describe Spree::Shipment do
       shipping_method.should_receive(:build_tracking_url).with('1Z12345').and_return(:some_url)
       shipment.tracking = '1Z12345'
 
-      shipment.tracking_url.should == :some_url
+      expect(shipment.tracking_url).to eq :some_url
     end
   end