Provide ViewComponent::Configurable module

This can be included on a module to provide module-local configuration for ViewComponent. It avoids overwriting existing configuration that may already exist.

Author: boardfish

lib/view_component/configurable.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module ViewComponent
+  module Configurable
+    extend ActiveSupport::Concern
+
+    included do
+      next if respond_to?(:config) && config.respond_to?(:view_component) && config.respond_to_missing?(:test_controller)
+
+      include ActiveSupport::Configurable
+
+      configure do |config|
+        config.view_component ||= ActiveSupport::InheritableOptions.new
+      end
+    end
+  end
+end

test/sandbox/test/base_test.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "test_helper"
+require "view_component/configurable"
 
 class ViewComponent::Base::UnitTest < Minitest::Test
   def test_identifier
@@ -149,27 +150,51 @@ def test_no_method_error_does_not_reference_missing_helper
 
   module TestModuleWithoutConfig
     class SomeComponent < ViewComponent::Base
-
     end
   end
 
   # Config defined on top-level module as opposed to engine.
   module TestModuleWithConfig
+    include ViewComponent::Configurable
+
+    configure do |config|
+      config.view_component.test_controller = "AnotherController"
+    end
+
+    class SomeComponent < ViewComponent::Base
+    end
+  end
+
+  module TestAlreadyConfigurableModule
     include ActiveSupport::Configurable
+    include ViewComponent::Configurable
 
     configure do |config|
-      # To get this green.
-      config.view_component = ActiveSupport::InheritableOptions.new
       config.view_component.test_controller = "AnotherController"
     end
 
     class SomeComponent < ViewComponent::Base
     end
   end
 
+  module TestAlreadyConfiguredModule
+    include ActiveSupport::Configurable
+
+    configure do |config|
+      config.view_component = ActiveSupport::InheritableOptions[test_controller: "AnotherController"]
+    end
+
+    include ViewComponent::Configurable
+
+    class SomeComponent < ViewComponent::Base
+    end
+  end
+
   def test_uses_module_configuration
     # We override this ourselves in test/sandbox/config/environments/test.rb.
     assert_equal "IntegrationExamplesController", TestModuleWithoutConfig::SomeComponent.test_controller
     assert_equal "AnotherController", TestModuleWithConfig::SomeComponent.test_controller
+    assert_equal "AnotherController", TestAlreadyConfigurableModule::SomeComponent.test_controller
+    assert_equal "AnotherController", TestAlreadyConfiguredModule::SomeComponent.test_controller
   end
 end