maintain 3.x deferred initializer block config

In 3.x the initializer config blocks are intentionally deferred to allow
referencing model classes without quoting. Here is a first pass at keeping that
behavior on top of ec03eb6. It could probably use a little cleanup but here's
an idea of an approach for feedback.

See
railsadminteam#3492 (comment)
for details.

.rubocop.yml

@@ -115,10 +115,10 @@ Metrics/CyclomaticComplexity:
 
 Metrics/MethodLength:
   CountComments: false
-  Max: 29 # TODO: Lower to 15
+  Max: 30 # TODO: Lower to 15
 
 Metrics/ModuleLength:
-  Max: 228 # TODO: Lower to 100
+  Max: 248 # TODO: Lower to 100
 
 Metrics/ParameterLists:
   Max: 8 # TODO: Lower to 4

lib/rails_admin.rb

@@ -29,9 +29,7 @@ def self.config(entity = nil, &block)
     if entity
       RailsAdmin::Config.model(entity, &block)
     elsif block_given?
-      # Immediately evaluate non-model (initializer) config. It's needed to
-      # properly configure routes when there are custom actions.
-      yield RailsAdmin::Config
+      RailsAdmin::Config.apply_core(&block)
     else
       RailsAdmin::Config
     end

lib/rails_admin/config.rb

@@ -23,9 +23,12 @@ module Config
     DEFAULT_CURRENT_USER = proc {}
 
     # Variables to track initialization process
-    @initialized = false
-    @initializing = false
-    @deferred_blocks = []
+    @initialized_core = false
+    @initializing_core = false
+    @deferred_core_blocks = []
+    @initialized_models = false
+    @initializing_models = false
+    @deferred_model_blocks = []
 
     class << self
       # Application title, can be an array of two elements
@@ -86,22 +89,42 @@ class << self
       # Set where RailsAdmin fetches JS/CSS from, defaults to :sprockets
       attr_writer :asset_source
 
-      # Finish initialization by executing deferred configuration blocks
-      def initialize!
-        return if @initializing
+      # Finish initialization by executing deferred non-model configuration blocks
+      def initialize_core!
+        return if @initializing_core
 
-        @initializing = true
-        @deferred_blocks.each { |block| block.call(self) }
-        @deferred_blocks.clear
-        @initialized = true
+        @initializing_core = true
+        @deferred_core_blocks.each { |block| block.call(self) }
+        @deferred_core_blocks.clear
+        @initialized_core = true
       end
 
-      # Evaluate the given block either immediately or lazily, based on initialization status.
-      def apply(&block)
-        if @initialized
+      # Evaluate the given non-model block either immediately or lazily, based on initialization status.
+      def apply_core(&block)
+        if @initialized_core
           yield(self)
         else
-          @deferred_blocks << block
+          @deferred_core_blocks << block
+        end
+      end
+
+      # Finish initialization by executing deferred model configuration blocks
+      def initialize_models!
+        return if @initializing_models
+
+        initialize_core!
+        @initializing_models = true
+        @deferred_model_blocks.each { |block| block.call(self) }
+        @deferred_model_blocks.clear
+        @initialized_models = true
+      end
+
+      # Evaluate the given model block either immediately or lazily, based on initialization status.
+      def apply_model(&block)
+        if @initialized_models
+          yield(self)
+        else
+          @deferred_model_blocks << block
         end
       end
 
@@ -230,7 +253,7 @@ def default_search_operator=(operator)
 
       # pool of all found model names from the whole application
       def models_pool
-        initialize!
+        initialize_models!
         (viable_models - excluded_models.collect(&:to_s)).uniq.sort
       end
 
@@ -268,13 +291,13 @@ def model(entity, &block)
         #
         # Do not defer when called without a block as the model must be returned.
         if block
-          RailsAdmin::Config.apply do
+          RailsAdmin::Config.apply_model do
             m = model(entity)
             m.instance_eval(&block) if @registry[key].abstract_model
           end
           nil
         else
-          initialize!
+          initialize_models!
           @registry[key] ||= RailsAdmin::Config::Model.new(entity)
         end
       end
@@ -338,8 +361,10 @@ def models
       #
       # @see RailsAdmin::Config.registry
       def reset
-        @initialized = @initializing = false
-        @deferred_blocks.clear
+        @initialized_core = @initializing_core = false
+        @deferred_core_blocks.clear
+        @initialized_models = @initializing_models = false
+        @deferred_model_blocks.clear
         @compact_show_view = true
         @browser_validations = true
         @authenticate = nil
@@ -380,6 +405,7 @@ def reset_model(model)
       def reload!
         reset
         load RailsAdmin::Engine.config.initializer_path
+        initialize_core!
       end
 
       # Get all models that are configured as visible sorted by their weight and label.

lib/rails_admin/engine.rb

@@ -68,6 +68,11 @@ class Engine < Rails::Engine
         ERROR
       end
 
+      RailsAdmin::Config.initialize_core!
+
+      # Force route reload, since it doesn't reflect RailsAdmin action configuration yet
+      app.reload_routes!
+
       RailsAdmin::Version.warn_with_js_version
     end
   end

spec/dummy_app/config/initializers/rails_admin.rb

@@ -2,7 +2,7 @@
 
 RailsAdmin.config do |c|
   c.asset_source = CI_ASSET
-  c.model 'Team' do
+  c.model Team do
     include_all_fields
     field :color, :color
   end

spec/rails_admin/config_spec.rb

@@ -395,41 +395,44 @@ class TestController < ActionController::Base; end
     end
   end
 
-  describe '.apply' do
-    subject { RailsAdmin::Config.apply(&block) }
+  describe '.apply_core' do
+    subject { RailsAdmin::Config.apply_core(&block) }
     let(:block) do
       proc do |config|
         config.model Team do
           register_instance_option('parameter') # an arbitrary instance method we can spy on
         end
       end
     end
-    before { RailsAdmin::Config.instance_variable_set(:@initialized, false) }
-    before { RailsAdmin::Config.instance_variable_set(:@initializing, false) }
-    after do
-      RailsAdmin::Config.instance_variable_set(:@initialized, true)
-      RailsAdmin::Config.instance_variable_set(:@deferred_blocks, [])
-    end
+    after { RailsAdmin::Config.reset }
 
     it "doesn't evaluate the block immediately" do
       expect_any_instance_of(RailsAdmin::Config::Model).not_to receive(:register_instance_option)
       subject
     end
 
-    it 'evaluates block when initialize! is finished' do
+    it "doesn't evaluate the block when initialize_core! is finished" do
+      expect_any_instance_of(RailsAdmin::Config::Model).not_to receive(:register_instance_option).with('parameter')
+      subject
+      RailsAdmin::Config.initialize_core!
+    end
+
+    it 'evaluates block when initialize_models! is finished' do
       expect_any_instance_of(RailsAdmin::Config::Model).to receive(:register_instance_option).with('parameter')
       subject
-      RailsAdmin::Config.initialize!
+      RailsAdmin::Config.initialize_models!
     end
 
     it 'evaluates config block only once' do
       expect_any_instance_of(RailsAdmin::Config::Model).to receive(:register_instance_option).once.with('parameter')
       subject
-      RailsAdmin::Config.initialize!
-      RailsAdmin::Config.initialize!
+      RailsAdmin::Config.initialize_models!
+      RailsAdmin::Config.initialize_models!
     end
 
     context 'with a non-existent class' do
+      before { RailsAdmin::Config.reset }
+
       let(:block) do
         proc do |config|
           config.model UnknownClass do
@@ -465,7 +468,7 @@ class TestController < ActionController::Base; end
     end
 
     it 'does not immediately apply model configuration' do
-      expect(RailsAdmin::Config).not_to receive(:initialize!)
+      expect(RailsAdmin::Config).not_to receive(:initialize_models!)
       RailsAdmin::Config.reload!
     end
 

spec/spec_helper.rb

@@ -93,6 +93,7 @@
     DatabaseCleaner.start
     RailsAdmin::Config.reset
     RailsAdmin::Config.asset_source = CI_ASSET
+    RailsAdmin::Config.initialize_core!
   end
 
   config.after(:each) do