Remove dummy_order and dummy_line_item helpers

These helpers are dangerous: they provide a false sense of assurance
by making you think that the order and the line item they return can
be used to infer the correct total value of future subscription orders.

In reality, order calculation in Solidus is an extremely complex process
that may take a ton of different parameters into account, and each store
is better off calculating the subscription total with their custom logic
rather than this extension trying to provide a solution that works for
everyone.

In the future, we may provide a way to compute a subscription's total,
but for the time being it's better to remove the helpers altogether.

README.md

@@ -62,8 +62,7 @@ This will associate a `SolidusSubscriptions::LineItem` to the line item being ad
 
 The customer will not be charged for the subscription until it is processed. The subscription line
 items should be shown to the user on the cart page by looping over
-`Spree::Order#subscription_line_items`. `SolidusSubscriptions::LineItem#dummy_line_item` may be
-useful to help you display the subscription line item with your existing cart infrastructure.
+`Spree::Order#subscription_line_items`.
 
 When the order is finalized, a `SolidusSubscriptions::Subscription` will be created for each group
 of subscription line items which can be fulfilled by a single subscription.

app/models/solidus_subscriptions/installment.rb

@@ -31,13 +31,6 @@ class Installment < ApplicationRecord
       unfulfilled.where("#{table_name}.actionable_date <= ?", Time.zone.today)
     end)
 
-    # Get the builder for the subscription_line_item. This will be an
-    # object that can generate the appropriate line item for the subscribable
-    # object
-    #
-    # @return [SolidusSubscriptions::LineItemBuilder]
-    delegate :line_item_builder, to: :subscription
-
     # Mark this installment as out of stock.
     #
     # @return [SolidusSubscriptions::InstallmentDetail] The record of the failed

app/models/solidus_subscriptions/line_item.rb

@@ -38,34 +38,5 @@ class LineItem < ApplicationRecord
     validates :subscribable_id, presence: true
     validates :quantity, numericality: { greater_than: 0 }
     validates :interval_length, numericality: { greater_than: 0 }, unless: -> { subscription }
-
-    def as_json(**options)
-      options[:methods] ||= [:dummy_line_item]
-      super(options)
-    end
-
-    # Get a placeholder line item for calculating the values of future
-    # subscription orders. It is frozen and cannot be saved
-    def dummy_line_item
-      li = LineItemBuilder.new([self]).spree_line_items.first
-      return unless li
-
-      li.order = dummy_order
-      li.validate
-      li.freeze
-    end
-
-    private
-
-    # Get a placeholder order for calculating the values of future
-    # subscription orders. It is a frozen duplicate of the current order and
-    # cannot be saved
-    def dummy_order
-      order = spree_line_item ? spree_line_item.order.dup : ::Spree::Order.create
-      order.ship_address = subscription.shipping_address || subscription.user.ship_address if subscription
-      order.bill_address = subscription.billing_address || subscription.user.bill_address if subscription
-
-      order.freeze
-    end
   end
 end

app/models/solidus_subscriptions/subscription.rb

@@ -203,15 +203,6 @@ def advance_actionable_date
       actionable_date
     end
 
-    # Get the builder for the subscription_line_item. This will be an
-    # object that can generate the appropriate line item for the subscribable
-    # object
-    #
-    # @return [SolidusSubscriptions::LineItemBuilder]
-    def line_item_builder
-      LineItemBuilder.new(line_items)
-    end
-
     # The state of the last attempt to process an installment associated to
     # this subscription
     #

lib/solidus_subscriptions.rb

@@ -19,7 +19,6 @@
 require 'solidus_subscriptions/churn_buster/subscription_serializer'
 require 'solidus_subscriptions/churn_buster/order_serializer'
 require 'solidus_subscriptions/checkout'
-require 'solidus_subscriptions/line_item_builder'
 require 'solidus_subscriptions/subscription_generator'
 require 'solidus_subscriptions/subscription_line_item_builder'
 require 'solidus_subscriptions/dispatcher/base'

spec/models/solidus_subscriptions/installment_spec.rb

@@ -5,15 +5,6 @@
 
   it { is_expected.to validate_presence_of :subscription }
 
-  describe '#line_item_builder' do
-    subject { installment.line_item_builder }
-
-    let(:line_items) { installment.subscription.line_items }
-
-    it { is_expected.to be_a SolidusSubscriptions::LineItemBuilder }
-    it { is_expected.to have_attributes(subscription_line_items: line_items) }
-  end
-
   describe '#out_of_stock' do
     subject { installment.out_of_stock }
 

spec/models/solidus_subscriptions/line_item_spec.rb

@@ -24,90 +24,4 @@
       expect(subject.from_now).to eq Date.parse("2016-10-22")
     end
   end
-
-  describe '#as_json' do
-    subject { line_item.as_json }
-
-    around { |e| Timecop.freeze { e.run } }
-
-    let(:line_item) { create(:subscription_line_item, :with_subscription) }
-
-    let(:expected_hash) do
-      hash = {
-        "id" => line_item.id,
-        "spree_line_item_id" => line_item.spree_line_item.id,
-        "subscription_id" => line_item.subscription_id,
-        "quantity" => line_item.quantity,
-        "end_date" => line_item.end_date,
-        "subscribable_id" => line_item.subscribable_id,
-        "created_at" => line_item.created_at,
-        "updated_at" => line_item.updated_at,
-        "interval_units" => line_item.interval_units,
-        "interval_length" => line_item.interval_length
-      }
-      Rails.gem_version >= Gem::Version.new('6.0.0') ? hash.as_json : hash
-    end
-
-    it 'includes the attribute values' do
-      expect(subject).to match a_hash_including(expected_hash)
-    end
-
-    it 'includes the dummy lineitem' do
-      expect(subject).to have_key('dummy_line_item')
-    end
-  end
-
-  describe '#dummy_line_item' do
-    subject { line_item.dummy_line_item }
-
-    let(:line_item) { create(:subscription_line_item, :with_subscription) }
-
-    it { is_expected.to be_a Spree::LineItem }
-    it { is_expected.to be_frozen }
-
-    it 'has the correct variant' do
-      expect(subject.variant_id).to eq line_item.subscribable_id
-    end
-
-    context 'with no spree line item' do
-      let(:line_item) { create(:subscription_line_item, :with_subscription, spree_line_item: nil) }
-
-      it { is_expected.to be_a Spree::LineItem }
-      it { is_expected.to be_frozen }
-
-      it 'has the correct variant' do
-        expect(subject.variant_id).to eq line_item.subscribable_id
-      end
-    end
-
-    context 'with an associated subscription' do
-      context 'the associated subscription has a shipping address' do
-        let(:line_item) do
-          create(:subscription_line_item, :with_subscription, subscription_traits: [:with_shipping_address])
-        end
-
-        it 'uses the subscription shipping address' do
-          expect(subject.order.ship_address).to eq line_item.subscription.shipping_address
-        end
-
-        it 'uses the subscription users billing address' do
-          expect(subject.order.bill_address).to eq line_item.subscription.user.bill_address
-        end
-      end
-
-      context 'the associated subscription has a billing address' do
-        let(:line_item) do
-          create(:subscription_line_item, :with_subscription, subscription_traits: [:with_billing_address])
-        end
-
-        it 'uses the subscription users shipping address' do
-          expect(subject.order.ship_address).to eq line_item.subscription.user.ship_address
-        end
-
-        it 'uses the subscription billing address' do
-          expect(subject.order.bill_address).to eq line_item.subscription.billing_address
-        end
-      end
-    end
-  end
 end

spec/models/solidus_subscriptions/subscription_spec.rb

@@ -348,16 +348,6 @@
     end
   end
 
-  describe '#line_item_builder' do
-    subject { subscription.line_item_builder }
-
-    let(:subscription) { create :subscription, :with_line_item }
-    let(:line_items) { subscription.line_items }
-
-    it { is_expected.to be_a SolidusSubscriptions::LineItemBuilder }
-    it { is_expected.to have_attributes(subscription_line_items: line_items) }
-  end
-
   describe '#processing_state' do
     subject { subscription.processing_state }