Change condition configuration to be flat

Prior to this commit, we had three configuration options for conditions:
`SolidusPromotions.config.order_conditions`,
`SolidusPromotions.config.line_item_conditions`, and
`SolidusPromotions.config.shipment_conditions`.

Conditions can, however, also target shipping rates, and future
iterations of the promotion system will need conditions that can target
arbitary objects like `Spree::Product` instances or `Spree::Price`
instances.

This commit changes the configuration to simply be
`SolidusPromotions.config.conditions` and uses a small bit of
metaprogramming to see whether a condition is applicable to an object,
and thus paves the way for promotions on prices, products, and taxons.

Author: mamhoff

promotions/app/models/solidus_promotions/benefit.rb

@@ -64,6 +64,19 @@ class Benefit < Spree::Base
     #   @return [ActiveRecord::Relation<SolidusPromotions::Benefit>]
     scope :of_type, ->(type) { where(type: Array.wrap(type).map(&:to_s)) }
 
+    # Base set of order-level condition classes available to all benefits.
+    #
+    # These generic order conditions apply regardless of the concrete benefit
+    # type, as every benefit ultimately operates within the context of an order.
+    # Concrete benefit subclasses may extend or override this to include
+    # additional applicable conditions that are specific to their discount
+    # target (e.g., line-item or shipment conditions).
+    #
+    # @return [Enumerable<Class<SolidusPromotions::Condition>>]
+    def self.possible_conditions
+      SolidusPromotions::Condition.applicable_to([Spree::Order])
+    end
+
     # Returns relations that should be preloaded for this condition.
     #
     # Override this method in subclasses to specify associations that should be eager loaded
@@ -237,7 +250,7 @@ def level
     #
     # @return [Set<Class<SolidusPromotions::Condition>>]
     def available_conditions
-      possible_conditions - conditions.select(&:persisted?)
+      self.class.possible_conditions - conditions.select(&:persisted?)
     end
 
     # Returns the calculators allowed for this benefit type.
@@ -302,7 +315,8 @@ def applicable_line_items(order)
     #
     # @return [Set<Class<SolidusPromotions::Condition>>]
     def possible_conditions
-      Set.new(SolidusPromotions.config.order_conditions)
+      Spree.deprecator.warn("Use #{self.class.name}.possible_conditions instead.")
+      self.class.possible_conditions
     end
 
     private

promotions/app/models/solidus_promotions/benefits/adjust_line_item.rb

@@ -3,17 +3,17 @@
 module SolidusPromotions
   module Benefits
     class AdjustLineItem < Benefit
+      def self.possible_conditions
+        SolidusPromotions::Condition.applicable_to([Spree::Order, Spree::LineItem])
+      end
+
       def discount_line_item(line_item, ...)
         adjustment = find_adjustment(line_item) || build_adjustment(line_item)
         adjustment.amount = compute_amount(line_item, ...)
         adjustment.label = adjustment_label(line_item)
         adjustment
       end
 
-      def possible_conditions
-        super + SolidusPromotions.config.line_item_conditions
-      end
-
       def level
         :line_item
       end

promotions/app/models/solidus_promotions/benefits/adjust_shipment.rb

@@ -3,6 +3,10 @@
 module SolidusPromotions
   module Benefits
     class AdjustShipment < Benefit
+      def self.possible_conditions
+        SolidusPromotions::Condition.applicable_to([Spree::Order, Spree::Shipment])
+      end
+
       def discount_shipment(shipment, ...)
         adjustment = find_adjustment(shipment) || build_adjustment(shipment)
         adjustment.amount = compute_amount(shipment, ...)
@@ -17,10 +21,6 @@ def discount_shipping_rate(shipping_rate, ...)
         discount
       end
 
-      def possible_conditions
-        super + SolidusPromotions.config.shipment_conditions
-      end
-
       def level
         :shipment
       end

promotions/app/models/solidus_promotions/condition.rb

@@ -54,6 +54,27 @@ class Condition < Spree::Base
     validate :unique_per_benefit, on: :create
     validate :possible_condition_for_benefit, if: -> { benefit.present? }
 
+    class << self
+      # Returns the subset of conditions that can compute eligibility instances of the provided array of classes.
+      #
+      # @example SolidusPromotions::Condition.applicable_to([Spree::Order, Spree::LineItem])
+      #
+      # @param [Array<Class>] An array of classes to compute eligibility for
+      # @return [Array<SolidusPromotions::Condition>] Conditions that can compute eligibility for the provided classes.
+      def applicable_to(classes)
+        SolidusPromotions.config.conditions.select do |condition_class|
+          (condition_class.instance_methods & classes.map { |k| eligible_method_for(k) }).any?
+        end
+      end
+
+      # Generates the eligibility method name for a promotable
+      #
+      # @return [Symbol] the method name
+      def eligible_method_for(promotable_class)
+        :"#{promotable_class.name.demodulize.underscore}_eligible?"
+      end
+    end
+
     # Returns relations that should be preloaded for this condition.
     #
     # Override this method in subclasses to specify associations that should be eager loaded
@@ -178,11 +199,8 @@ def updateable?
 
     private
 
-    # Generates the eligibility method name for a promotable
-    #
-    # @return [Symbol] the method name
     def eligible_method_for(promotable)
-      :"#{promotable.class.name.demodulize.underscore}_eligible?"
+      self.class.eligible_method_for(promotable.class)
     end
 
     # Validates that only one instance of this condition type exists per benefit.
@@ -199,7 +217,7 @@ def unique_per_benefit
     # Checks the benefit's {Benefit#possible_conditions} to ensure this condition
     # type is compatible.
     def possible_condition_for_benefit
-      benefit.possible_conditions.include?(self.class) || errors.add(:type, :invalid_condition_type)
+      benefit.class.possible_conditions.include?(self.class) || errors.add(:type, :invalid_condition_type)
     end
 
     # Generates a translated eligibility error message.

promotions/lib/solidus_promotions/configuration.rb

@@ -32,7 +32,37 @@ class Configuration < Spree::Preferences::Configuration
     # In case solidus_legacy_promotions is loaded, we need to define this.
     class_name_attribute :shipping_promotion_handler_class, default: "Spree::NullPromotionHandler"
 
-    add_class_set :order_conditions, default: [
+    def order_conditions
+      SolidusPromotions::Condition.applicable_to([Spree::Order])
+    end
+    deprecate order_conditions: :conditions, deprecator: Spree.deprecator
+
+    def order_conditions=(conditions)
+      conditions.each { self.conditions << _1 }
+    end
+    deprecate :order_conditions= => :conditions=, :deprecator => Spree.deprecator
+
+    def line_item_conditions
+      SolidusPromotions::Condition.applicable_to([Spree::LineItem])
+    end
+    deprecate line_item_conditions: :conditions, deprecator: Spree.deprecator
+
+    def line_item_conditions=(conditions)
+      conditions.each { self.conditions << _1 }
+    end
+    deprecate :line_item_conditions= => :conditions=, :deprecator => Spree.deprecator
+
+    def shipment_conditions
+      SolidusPromotions::Condition.applicable_to([Spree::Shipment])
+    end
+    deprecate shipment_conditions: :conditions, deprecator: Spree.deprecator
+
+    def shipment_conditions=(conditions)
+      conditions.each { self.conditions << _1 }
+    end
+    deprecate :shipment_conditions= => :conditions=, :deprecator => Spree.deprecator
+
+    add_class_set :conditions, default: [
       "SolidusPromotions::Conditions::FirstOrder",
       "SolidusPromotions::Conditions::FirstRepeatPurchaseSince",
       "SolidusPromotions::Conditions::ItemTotal",
@@ -49,15 +79,10 @@ class Configuration < Spree::Preferences::Configuration
       "SolidusPromotions::Conditions::OrderTaxon",
       "SolidusPromotions::Conditions::UserLoggedIn",
       "SolidusPromotions::Conditions::UserRole",
-      "SolidusPromotions::Conditions::User"
-    ]
-
-    add_class_set :line_item_conditions, default: [
+      "SolidusPromotions::Conditions::User",
       "SolidusPromotions::Conditions::LineItemOptionValue",
       "SolidusPromotions::Conditions::LineItemProduct",
-      "SolidusPromotions::Conditions::LineItemTaxon"
-    ]
-    add_class_set :shipment_conditions, default: [
+      "SolidusPromotions::Conditions::LineItemTaxon",
       "SolidusPromotions::Conditions::ShippingMethod"
     ]
 

promotions/spec/lib/solidus_promotions/configuration_spec.rb

@@ -3,7 +3,7 @@
 require "rails_helper"
 
 RSpec.describe SolidusPromotions::Configuration do
-  subject(:config) { SolidusPromotions.config }
+  subject(:config) { described_class.new }
 
   it "has a nice accessor" do
     expect(subject).to be_a(described_class)
@@ -31,20 +31,53 @@
     it { is_expected.to be_a(Spree::Core::NestedClassSet) }
   end
 
-  describe ".order_conditions" do
+  describe ".order_conditions", :silence_deprecations do
     subject { config.order_conditions }
 
-    it { is_expected.to be_a(Spree::Core::ClassConstantizer::Set) }
+    it { is_expected.to include(SolidusPromotions::Conditions::User) }
   end
 
-  describe ".line_item_conditions" do
+  describe ".line_item_conditions", :silence_deprecations do
     subject { config.line_item_conditions }
 
-    it { is_expected.to be_a(Spree::Core::ClassConstantizer::Set) }
+    it { is_expected.to include(SolidusPromotions::Conditions::LineItemProduct) }
   end
 
-  describe ".shipment_conditions" do
-    subject { config.line_item_conditions }
+  describe ".shipment_conditions", :silence_deprecations do
+    subject { config.shipment_conditions }
+
+    it { is_expected.to include(SolidusPromotions::Conditions::ShippingMethod) }
+  end
+
+  describe "deprecated condition setters", :silence_deprecations do
+    before do
+      stub_const("TestCondition", Class.new(SolidusPromotions::Condition))
+    end
+
+    describe "order_conditions=" do
+      it "adds conditions to the #conditions set" do
+        expect { config.order_conditions = [TestCondition] }.to change { config.conditions.count }.by(1)
+        expect(config.conditions).to include(TestCondition)
+      end
+    end
+
+    describe "line_item_conditions=" do
+      it "adds conditions to the #conditions set" do
+        expect { config.line_item_conditions = [TestCondition] }.to change { config.conditions.count }.by(1)
+        expect(config.conditions).to include(TestCondition)
+      end
+    end
+
+    describe "shipment_conditions=" do
+      it "adds conditions to the #conditions set" do
+        expect { config.shipment_conditions = [TestCondition] }.to change { config.conditions.count }.by(1)
+        expect(config.conditions).to include(TestCondition)
+      end
+    end
+  end
+
+  describe ".conditions" do
+    subject { config.conditions }
 
     it { is_expected.to be_a(Spree::Core::ClassConstantizer::Set) }
   end

promotions/spec/models/solidus_promotions/benefit_spec.rb

@@ -309,4 +309,16 @@ def line_item_adjustment_label(_line_item, _options = {})
       it { is_expected.to eq("Something entirely different") }
     end
   end
+
+  describe ".possible_conditions" do
+    subject { described_class.possible_conditions }
+
+    it { is_expected.to include(SolidusPromotions::Conditions::User) }
+  end
+
+  describe "#possible_conditions", :silence_deprecations do
+    subject { described_class.new.possible_conditions }
+
+    it { is_expected.to include(SolidusPromotions::Conditions::User) }
+  end
 end