Use ActiveSupport::Configurable to cascade config

ViewComponent::Base itself will always use the defaults. Any classes inheriting from ViewComponent::Base will cascade config down using InheritableOptions, only specifying any overrides.
Generate options being on their own "layer of config is currently unresolved - it might be that config needs to be a new object inheriting from InheritableOptions that has method accessors for everything in that namespace.

It seems like this solution is now applicable to everything, not just strict_helper_enabled?

lib/view_component/base.rb

@@ -43,16 +43,6 @@ def config
     class_attribute :__vc_strip_trailing_whitespace, instance_accessor: false, instance_predicate: false
     self.__vc_strip_trailing_whitespace = false # class_attribute:default doesn't work until Rails 5.2
 
-    # Default for class
-    class_attribute :__vc_strict_helpers_enabled, instance_accessor: false, instance_predicate: false, default: false
-    # Changeable for instance
-    attr_writer :__vc_strict_helpers_enabled
-
-    def __vc_strict_helpers_enabled
-      @__vc_strict_helpers_enabled.nil? ? self.class.__vc_strict_helpers_enabled : @__vc_strict_helpers_enabled
-    end
-    alias_method :strict_helpers_enabled?, :__vc_strict_helpers_enabled
-
     attr_accessor :__vc_original_view_context
 
     # Components render in their own view context. Helpers and other functionality
@@ -529,9 +519,16 @@ def inherited(child)
         # `compile` defines
         compile
 
-        # Set strict_helpers_enabled from global config
+        child.include ActiveSupport::Configurable
+
         if child.superclass == ViewComponent::Base
-          child.__vc_strict_helpers_enabled = Rails.application.config.view_component.strict_helpers_enabled
+          child.define_singleton_method(:config) do
+            @@config ||= Rails.application.config.view_component.inheritable_copy
+          end
+        else
+          child.define_singleton_method(:config) do
+            @@config ||= superclass.config.inheritable_copy
+          end
         end
 
         # Give the child its own personal #render_template_for to protect against the case when
@@ -655,15 +652,6 @@ def strip_trailing_whitespace?
         __vc_strip_trailing_whitespace
       end
 
-      # TODO
-      def strict_helpers_enabled=(value = true)
-        self.__vc_strict_helpers_enabled = value
-      end
-
-      def strict_helpers_enabled?
-        __vc_strict_helpers_enabled
-      end
-
       # Ensure the component initializer accepts the
       # collection parameter. By default, we don't
       # validate that the default parameter name

lib/view_component/config.rb

@@ -11,7 +11,7 @@ class << self
       alias_method :default, :new
 
       def defaults
-        ActiveSupport::OrderedOptions.new.merge!({
+        ActiveSupport::InheritableOptions.new({
           generate: default_generate_options,
           preview_controller: "ViewComponentsController",
           preview_route: "/rails/view_components",
@@ -26,7 +26,8 @@ def defaults
           test_controller: "ApplicationController",
           default_preview_layout: nil,
           capture_compatibility_patch_enabled: false,
-          helpers_enabled: true
+          helpers_enabled: true,
+          strict_helpers_enabled?: false
         })
       end
 

lib/view_component/engine.rb

@@ -6,7 +6,7 @@
 
 module ViewComponent
   class Engine < Rails::Engine # :nodoc:
-    config.view_component = ViewComponent::Config.current
+    config.view_component = ViewComponent::Config.defaults
 
     rake_tasks do
       load "view_component/rails/tasks/view_component.rake"

lib/view_component/use_helpers.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "view_component/errors"
+
 module ViewComponent::UseHelpers
   extend ActiveSupport::Concern
 
@@ -13,7 +15,7 @@ def use_helper(helper_method, from: nil, prefix: false)
 
       class_eval(<<-RUBY, __FILE__, __LINE__ + 1)
         def #{helper_method_name}(*args, &block)
-          raise HelpersCalledBeforeRenderError if view_context.nil?
+          raise ::ViewComponent::HelpersCalledBeforeRenderError if view_context.nil?
 
           #{define_helper(helper_method: helper_method, source: from)}
         end

test/sandbox/test/base_test.rb

@@ -157,18 +157,18 @@ def test_no_method_error_does_not_reference_missing_helper
 
   def test_strict_helpers_enabled
     with_config_option(:strict_helpers_enabled, false) do
-      refute ViewComponent::Base.strict_helpers_enabled?, ".strict_helpers_enabled? should be false by default"
-      refute ViewComponent::Base.new.strict_helpers_enabled?, "#strict_helpers_enabled? should be false by default"
-      Rails.application.config.view_component.strict_helpers_enabled = true
-      refute ViewComponent::Base.strict_helpers_enabled?, ".strict_helpers_enabled? should not be changed by global config for ViewComponent::Base"
-      refute ViewComponent::Base.new.strict_helpers_enabled?, "#strict_helpers_enabled? should not be changed by global config for ViewComponent::Base"
       top_level_component_class = Class.new(ViewComponent::Base)
-      assert top_level_component_class.strict_helpers_enabled?, ".strict_helpers_enabled? should inherit from global config"
-      assert top_level_component_class.new.strict_helpers_enabled?, "#strict_helpers_enabled? should inherit from global config"
-      top_level_component_class.strict_helpers_enabled = false
+      refute ViewComponent::Base.config.strict_helpers_enabled?, ".strict_helpers_enabled? should be false by default"
+      # refute ViewComponent::Base.new.config.strict_helpers_enabled?, "#strict_helpers_enabled? should be false by default"
+      Rails.application.config.view_component[:strict_helpers_enabled?] = true
+      refute ViewComponent::Base.config.strict_helpers_enabled?, ".strict_helpers_enabled? should not be changed by global config for ViewComponent::Base"
+      # refute ViewComponent::Base.new.config.strict_helpers_enabled?, "#strict_helpers_enabled? should not be changed by global config for ViewComponent::Base"
+      assert top_level_component_class.config.strict_helpers_enabled?, ".strict_helpers_enabled? should inherit from global config"
+      assert top_level_component_class.new.config.strict_helpers_enabled?, "#strict_helpers_enabled? should inherit from global config"
       inherited_component_class = Class.new(top_level_component_class)
-      refute inherited_component_class.strict_helpers_enabled?, ".strict_helpers_enabled? should inherit from its parent"
-      refute inherited_component_class.new.strict_helpers_enabled?, "#strict_helpers_enabled? should inherit from its parent"
+      top_level_component_class.config[:strict_helpers_enabled?] = false
+      refute inherited_component_class.config.strict_helpers_enabled?, ".strict_helpers_enabled? should inherit from its parent"
+      refute inherited_component_class.new.config.strict_helpers_enabled?, "#strict_helpers_enabled? should inherit from its parent"
     end
   end
 end