Merge pull request #1017 from bf4/registerable_adapters

Make Adapters registerable so they are not namespace-constrained
2026-01-22 22:06:50 +00:00 · 2015-09-11 02:24:37 -03:00 · 2015-09-11 02:24:37 -03:00 · 4399c1ad1a
commit 4399c1ad1a
parent 1388ae82f2 880f235f0f
20 changed files with 310 additions and 107 deletions
--- a/.gitignore
+++ b/.gitignore
@ -4,6 +4,7 @@
 .config
 .yardoc
 Gemfile.lock
+Gemfile.local
 InstalledFiles
 _yardoc
 coverage
--- a/.rubocop.yml
+++ b/.rubocop.yml
@ -8,6 +8,39 @@ AllCops:
  DisplayCopNames: true
  DisplayStyleGuide: true

+Style/IndentationConsistency:
+  Exclude:
+    - lib/active_model/serializer/adapter/flatten_json.rb
+    - lib/active_model/serializer/adapter/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json.rb
+    - lib/active_model/serializer/adapter/json/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api.rb
+    - lib/active_model/serializer/adapter/json_api/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api/pagination_links.rb
+    - lib/active_model/serializer/adapter/null.rb
+
+Style/IndentationWidth:
+  Exclude:
+    - lib/active_model/serializer/adapter/flatten_json.rb
+    - lib/active_model/serializer/adapter/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json.rb
+    - lib/active_model/serializer/adapter/json/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api.rb
+    - lib/active_model/serializer/adapter/json_api/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api/pagination_links.rb
+    - lib/active_model/serializer/adapter/null.rb
+
+Style/AccessModifierIndentation:
+  Exclude:
+    - lib/active_model/serializer/adapter/flatten_json.rb
+    - lib/active_model/serializer/adapter/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json.rb
+    - lib/active_model/serializer/adapter/json/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api.rb
+    - lib/active_model/serializer/adapter/json_api/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api/pagination_links.rb
+    - lib/active_model/serializer/adapter/null.rb
+
 Lint/NestedMethodDefinition:
  Enabled: false
  Exclude:
--- a/.simplecov
+++ b/.simplecov
@ -8,7 +8,7 @@
  when 'jruby', 'rbx'
    96.0
  else
-    98.3
+    98.1
  end
 }.to_f.round(2)
 # rubocop:disable Style/DoubleNegation
--- a/4
+++ b/4
@ -1,4 +1,8 @@
 source 'https://rubygems.org'
+#
+# Add a Gemfile.local to locally bundle gems outside of version control
+local_gemfile = File.join(File.expand_path('..', __FILE__), 'Gemfile.local')
+eval_gemfile local_gemfile if File.readable?(local_gemfile)

 # Specify your gem's dependencies in active_model_serializers.gemspec
 gemspec
--- a/docs/general/adapters.md
+++ b/docs/general/adapters.md
@ -32,7 +32,7 @@ resources in the `"included"` member when the resource names are included in the

 ## Choosing an adapter

-If you want to use a different adapter, such as JsonApi, you can change this in an initializer:
+If you want to use a specify a default adapter, such as JsonApi, you can change this in an initializer:

 ```ruby
 ActiveModel::Serializer.config.adapter = ActiveModel::Serializer::Adapter::JsonApi
@ -44,8 +44,59 @@ or
 ActiveModel::Serializer.config.adapter = :json_api
 ```

-If you want to have a root key in your responses you should use the Json adapter, instead of the default FlattenJson:
+If you want to have a root key for each resource in your responses, you should use the Json or
+JsonApi adapters instead of the default FlattenJson:

 ```ruby
 ActiveModel::Serializer.config.adapter = :json
 ```
+
+## Advanced adapter configuration
+
+### Registering an adapter
+
+The default adapter can be configured, as above, to use any class given to it.
+
+An adapter may also be specified, e.g. when rendering, as a class or as a symbol.
+If a symbol, then the adapter must be, e.g. `:great_example`,
+`ActiveModel::Serializer::Adapter::GreatExample`, or registered.
+
+There are two ways to register an adapter:
+
+1) The simplest, is to subclass `ActiveModel::Serializer::Adapter`, e.g. the below will
+register the `Example::UsefulAdapter` as `:useful_adapter`.
+
+```ruby
+module Example
+  class UsefulAdapter < ActiveModel::Serializer::Adapter
+  end
+end
+```
+
+You'll notice that the name it registers is the class name underscored, not the full namespace.
+
+Under the covers, when the `ActiveModel::Serializer::Adapter` is subclassed, it registers
+the subclass as `register(:useful_adapter, Example::UsefulAdapter)`
+
+2) Any class can be registered as an adapter by calling `register` directly on the
+`ActiveModel::Serializer::Adapter` class. e.g., the below registers `MyAdapter` as
+`:special_adapter`.
+
+```ruby
+class MyAdapter; end
+ActiveModel::Serializer::Adapter.register(:special_adapter, MyAdapter)
+```
+
+### Looking up an adapter
+
+| `ActiveModel::Serializer::Adapter.adapter_map` | A Hash of all known adapters { adapter_name => adapter_class } |
+| `ActiveModel::Serializer::Adapter.adapters`    | A (sorted) Array of all known adapter_names |
+| `ActiveModel::Serializer::Adapter.lookup(name_or_klass)` |  The adapter_class, else raises an `ActiveModel::Serializer::Adapter::UnknownAdapter` error |
+| `ActiveModel::Serializer::Adapter.adapter_class(adapter)` | delegates to `ActiveModel::Serializer::Adapter.lookup(adapter)` |
+| `ActiveModel::Serializer.adapter` | a convenience method for `ActiveModel::Serializer::Adapter.lookup(config.adapter)` |
+
+The registered adapter name is always a String, but may be looked up as a Symbol or String.
+Helpfully, the Symbol or String is underscored, so that `get(:my_adapter)` and `get("MyAdapter")`
+may both be used.
+
+For more information, see [the Adapter class on GitHub](https://github.com/rails-api/active_model_serializers/blob/master/lib/active_model/serializer/adapter.rb)
--- a/lib/active_model/serializable_resource.rb
+++ b/lib/active_model/serializable_resource.rb
@ -76,7 +76,7 @@ module ActiveModel
    private

    ActiveModelSerializers.silence_warnings do
-    attr_reader :resource, :adapter_opts, :serializer_opts
+      attr_reader :resource, :adapter_opts, :serializer_opts
    end
  end
 end
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@ -94,19 +94,9 @@ module ActiveModel
      end
    end

+    # @see ActiveModel::Serializer::Adapter.lookup
    def self.adapter
-      adapter_class = case config.adapter
-                      when Symbol
-                        ActiveModel::Serializer::Adapter.adapter_class(config.adapter)
-                      when Class
-                        config.adapter
-                      end
-      unless adapter_class
-        valid_adapters = Adapter.constants.map { |klass| ":#{klass.to_s.downcase}" }
-        raise ArgumentError, "Unknown adapter: #{config.adapter}. Valid adapters are: #{valid_adapters}"
-      end
-
-      adapter_class
+      ActiveModel::Serializer::Adapter.lookup(config.adapter)
    end

    def self.root_name
--- a/lib/active_model/serializer/adapter.rb
+++ b/lib/active_model/serializer/adapter.rb
@ -1,12 +1,15 @@
 module ActiveModel
  class Serializer
    class Adapter
+      UnknownAdapterError = Class.new(ArgumentError)
+      ADAPTER_MAP = {}
+      private_constant :ADAPTER_MAP if defined?(private_constant)
      extend ActiveSupport::Autoload
-      require 'active_model/serializer/adapter/json'
-      require 'active_model/serializer/adapter/json_api'
-      autoload :FlattenJson
-      autoload :Null
      autoload :FragmentCache
+      autoload :Json
+      autoload :JsonApi
+      autoload :Null
+      autoload :FlattenJson

      def self.create(resource, options = {})
        override = options.delete(:adapter)
@ -14,9 +17,67 @@ module ActiveModel
        klass.new(resource, options)
      end

+      # @see ActiveModel::Serializer::Adapter.lookup
      def self.adapter_class(adapter)
-        adapter_name = adapter.to_s.classify.sub('API', 'Api')
-        "ActiveModel::Serializer::Adapter::#{adapter_name}".safe_constantize
+        ActiveModel::Serializer::Adapter.lookup(adapter)
+      end
+
+      # Only the Adapter class has these methods.
+      # None of the sublasses have them.
+      class << ActiveModel::Serializer::Adapter
+        # @return Hash<adapter_name, adapter_class>
+        def adapter_map
+          ADAPTER_MAP
+        end
+
+        # @return [Array<Symbol>] list of adapter names
+        def adapters
+          adapter_map.keys.sort
+        end
+
+        # Adds an adapter 'klass' with 'name' to the 'adapter_map'
+        # Names are stringified and underscored
+        # @param [Symbol, String] name of the registered adapter
+        # @param [Class] klass - adapter class itself
+        # @example
+        #     AMS::Adapter.register(:my_adapter, MyAdapter)
+        def register(name, klass)
+          adapter_map.update(name.to_s.underscore => klass)
+          self
+        end
+
+        # @param  adapter [String, Symbol, Class] name to fetch adapter by
+        # @return [ActiveModel::Serializer::Adapter] subclass of Adapter
+        # @raise  [UnknownAdapterError]
+        def lookup(adapter)
+          # 1. return if is a class
+          return adapter if adapter.is_a?(Class)
+          adapter_name = adapter.to_s.underscore
+          # 2. return if registered
+          adapter_map.fetch(adapter_name) {
+            # 3. try to find adapter class from environment
+            adapter_class = find_by_name(adapter_name)
+            register(adapter_name, adapter_class)
+            adapter_class
+          }
+        rescue NameError, ArgumentError => e
+          failure_message =
+            "NameError: #{e.message}. Unknown adapter: #{adapter.inspect}. Valid adapters are: #{adapters}"
+          raise UnknownAdapterError, failure_message, e.backtrace
+        end
+
+        # @api private
+        def find_by_name(adapter_name)
+          adapter_name = adapter_name.to_s.classify.tr('API', 'Api')
+          ActiveModel::Serializer::Adapter.const_get(adapter_name.to_sym) or # rubocop:disable Style/AndOr
+            fail UnknownAdapterError
+        end
+        private :find_by_name
+      end
+
+      # Automatically register adapters when subclassing
+      def self.inherited(subclass)
+        ActiveModel::Serializer::Adapter.register(subclass.to_s.demodulize, subclass)
      end

      attr_reader :serializer
--- a/lib/active_model/serializer/adapter/flatten_json.rb
+++ b/lib/active_model/serializer/adapter/flatten_json.rb
@ -1,7 +1,4 @@
-module ActiveModel
-  class Serializer
-    class Adapter
-      class FlattenJson < Json
+class ActiveModel::Serializer::Adapter::FlattenJson < ActiveModel::Serializer::Adapter::Json
        def serializable_hash(options = {})
          super
          @result
@ -13,7 +10,4 @@ module ActiveModel
        def include_meta(json)
          json
        end
-      end
-    end
-  end
 end
--- a/lib/active_model/serializer/adapter/fragment_cache.rb
+++ b/lib/active_model/serializer/adapter/fragment_cache.rb
@ -1,7 +1,4 @@
-module ActiveModel
-  class Serializer
-    class Adapter
-      class FragmentCache
+class ActiveModel::Serializer::Adapter::FragmentCache
        attr_reader :serializer

        def initialize(adapter, serializer, options)
@ -75,7 +72,4 @@ module ActiveModel
        def to_valid_const_name(name)
          name.gsub('::', '_')
        end
-      end
-    end
-  end
 end
--- a/lib/active_model/serializer/adapter/json.rb
+++ b/lib/active_model/serializer/adapter/json.rb
@ -1,9 +1,7 @@
-require 'active_model/serializer/adapter/json/fragment_cache'
+class ActiveModel::Serializer::Adapter::Json < ActiveModel::Serializer::Adapter
+        extend ActiveSupport::Autoload
+        autoload :FragmentCache

-module ActiveModel
-  class Serializer
-    class Adapter
-      class Json < Adapter
        def serializable_hash(options = nil)
          options ||= {}
          if serializer.respond_to?(:each)
@ -44,9 +42,6 @@ module ActiveModel
        end

        def fragment_cache(cached_hash, non_cached_hash)
-          Json::FragmentCache.new().fragment_cache(cached_hash, non_cached_hash)
+          ActiveModel::Serializer::Adapter::Json::FragmentCache.new().fragment_cache(cached_hash, non_cached_hash)
        end
-      end
-    end
-  end
 end
--- a/lib/active_model/serializer/adapter/json/fragment_cache.rb
+++ b/lib/active_model/serializer/adapter/json/fragment_cache.rb
@ -1,14 +1,5 @@
-require 'active_model/serializer/adapter/fragment_cache'
-module ActiveModel
-  class Serializer
-    class Adapter
-      class Json < Adapter
-        class FragmentCache
+class ActiveModel::Serializer::Adapter::Json::FragmentCache
          def fragment_cache(cached_hash, non_cached_hash)
            non_cached_hash.merge cached_hash
          end
-        end
-      end
-    end
-  end
 end
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@ -1,10 +1,8 @@
-require 'active_model/serializer/adapter/json_api/fragment_cache'
-require 'active_model/serializer/adapter/json_api/pagination_links'
+class ActiveModel::Serializer::Adapter::JsonApi < ActiveModel::Serializer::Adapter
+        extend ActiveSupport::Autoload
+        autoload :PaginationLinks
+        autoload :FragmentCache

-module ActiveModel
-  class Serializer
-    class Adapter
-      class JsonApi < Adapter
        def initialize(serializer, options = {})
          super
          @hash = { data: [] }
@ -49,7 +47,7 @@ module ActiveModel

        def fragment_cache(cached_hash, non_cached_hash)
          root = false if @options.include?(:include)
-          JsonApi::FragmentCache.new.fragment_cache(root, cached_hash, non_cached_hash)
+          ActiveModel::Serializer::Adapter::JsonApi::FragmentCache.new().fragment_cache(root, cached_hash, non_cached_hash)
        end

        private
@ -62,6 +60,12 @@ module ActiveModel
          end
        end

+        def add_relationships(resource, name, serializers)
+          resource[:relationships] ||= {}
+          resource[:relationships][name] ||= { data: [] }
+          resource[:relationships][name][:data] += serializers.map { |serializer| { type: serializer.json_api_type, id: serializer.id.to_s } }
+        end
+
        def resource_identifier_id_for(serializer)
          if serializer.respond_to?(:id)
            serializer.id
@ -161,8 +165,8 @@ module ActiveModel
          @hash[:links] = add_pagination_links(links, collection, options) if paginated?(collection)
        end

-        def add_pagination_links(links, collection, options)
-          pagination_links = JsonApi::PaginationLinks.new(collection, options[:context]).serializable_hash(options)
+        def add_pagination_links(links, resources, options)
+          pagination_links = ActiveModel::Serializer::Adapter::JsonApi::PaginationLinks.new(resources, options[:context]).serializable_hash(options)
          links.update(pagination_links)
        end

@ -171,7 +175,4 @@ module ActiveModel
            collection.respond_to?(:total_pages) &&
            collection.respond_to?(:size)
        end
-      end
-    end
-  end
 end
--- a/lib/active_model/serializer/adapter/json_api/fragment_cache.rb
+++ b/lib/active_model/serializer/adapter/json_api/fragment_cache.rb
@ -1,9 +1,4 @@
-require 'active_model/serializer/adapter/fragment_cache'
-module ActiveModel
-  class Serializer
-    class Adapter
-      class JsonApi < Adapter
-        class FragmentCache
+class ActiveModel::Serializer::Adapter::JsonApi::FragmentCache
          def fragment_cache(root, cached_hash, non_cached_hash)
            hash              = {}
            core_cached       = cached_hash.first
@ -15,8 +10,4 @@ module ActiveModel

            hash.deep_merge no_root_non_cache.deep_merge no_root_cache
          end
-        end
-      end
-    end
-  end
 end
--- a/lib/active_model/serializer/adapter/json_api/pagination_links.rb
+++ b/lib/active_model/serializer/adapter/json_api/pagination_links.rb
@ -1,8 +1,4 @@
-module ActiveModel
-  class Serializer
-    class Adapter
-      class JsonApi < Adapter
-        class PaginationLinks
+class ActiveModel::Serializer::Adapter::JsonApi::PaginationLinks
          FIRST_PAGE = 1

          attr_reader :collection, :context
@ -51,8 +47,4 @@ module ActiveModel
          def query_parameters
            @query_parameters ||= context.query_parameters
          end
-        end
-      end
-    end
-  end
 end
--- a/lib/active_model/serializer/adapter/null.rb
+++ b/lib/active_model/serializer/adapter/null.rb
@ -1,11 +1,5 @@
-module ActiveModel
-  class Serializer
-    class Adapter
-      class Null < Adapter
+class ActiveModel::Serializer::Adapter::Null < ActiveModel::Serializer::Adapter
        def serializable_hash(options = nil)
          {}
        end
-      end
-    end
-  end
 end
--- a/lib/active_model/serializer/fieldset.rb
+++ b/lib/active_model/serializer/fieldset.rb
@ -18,7 +18,7 @@ module ActiveModel
      private

      ActiveModelSerializers.silence_warnings do
-      attr_reader :raw_fields, :root
+        attr_reader :raw_fields, :root
      end

      def parsed_fields
--- a/test/action_controller/serialization_scope_name_test.rb
+++ b/test/action_controller/serialization_scope_name_test.rb
@ -25,7 +25,7 @@ class DefaultScopeNameTest < ActionController::TestCase
    end
  end

- tests UserTestController
+  tests UserTestController

  def test_default_scope_name
    get :render_new_user
--- a/test/adapter_test.rb
+++ b/test/adapter_test.rb
@ -19,16 +19,6 @@ module ActiveModel
        assert_equal @serializer, @adapter.serializer
      end

-      def test_adapter_class_for_known_adapter
-        klass = ActiveModel::Serializer::Adapter.adapter_class(:json_api)
-        assert_equal ActiveModel::Serializer::Adapter::JsonApi, klass
-      end
-
-      def test_adapter_class_for_unknown_adapter
-        klass = ActiveModel::Serializer::Adapter.adapter_class(:json_simple)
-        assert_nil klass
-      end
-
      def test_create_adapter
        adapter = ActiveModel::Serializer::Adapter.create(@serializer)
        assert_equal ActiveModel::Serializer::Adapter::FlattenJson, adapter.class
--- a/test/serializers/adapter_for_test.rb
+++ b/test/serializers/adapter_for_test.rb
@ -1,8 +1,15 @@
 module ActiveModel
  class Serializer
    class AdapterForTest < Minitest::Test
+      UnknownAdapterError = ::ActiveModel::Serializer::Adapter::UnknownAdapterError
+
      def setup
        @previous_adapter = ActiveModel::Serializer.config.adapter
+        # Eager load adapters
+        ActiveModel::Serializer::Adapter.eager_load!
+        [:json_api, :flatten_json, :null, :json].each do |adapter_name|
+          ActiveModel::Serializer::Adapter.lookup(adapter_name)
+        end
      end

      def teardown
@ -20,6 +27,7 @@ module ActiveModel
        adapter = ActiveModel::Serializer.adapter
        assert_equal ActiveModel::Serializer::Adapter::Null, adapter
      ensure
+        ActiveModel::Serializer.config.adapter = @previous_adapter
      end

      def test_overwrite_adapter_with_class
@ -32,7 +40,7 @@ module ActiveModel
      def test_raises_exception_if_invalid_symbol_given
        ActiveModel::Serializer.config.adapter = :unknown

-        assert_raises ArgumentError do
+        assert_raises UnknownAdapterError do
          ActiveModel::Serializer.adapter
        end
      end
@ -40,10 +48,123 @@ module ActiveModel
      def test_raises_exception_if_it_does_not_know_hot_to_infer_adapter
        ActiveModel::Serializer.config.adapter = 42

-        assert_raises ArgumentError do
+        assert_raises UnknownAdapterError do
          ActiveModel::Serializer.adapter
        end
      end
+
+      def test_adapter_class_for_known_adapter
+        klass = ActiveModel::Serializer::Adapter.adapter_class(:json_api)
+        assert_equal ActiveModel::Serializer::Adapter::JsonApi, klass
+      end
+
+      def test_adapter_class_for_unknown_adapter
+        assert_raises UnknownAdapterError do
+          ActiveModel::Serializer::Adapter.adapter_class(:json_simple)
+        end
+      end
+
+      def test_adapter_map
+        expected_adapter_map = {
+          'json'.freeze              => ActiveModel::Serializer::Adapter::Json,
+          'json_api'.freeze          => ActiveModel::Serializer::Adapter::JsonApi,
+          'flatten_json'.freeze      => ActiveModel::Serializer::Adapter::FlattenJson,
+          'null'.freeze              => ActiveModel::Serializer::Adapter::Null
+        }
+        assert_equal ActiveModel::Serializer::Adapter.adapter_map, expected_adapter_map
+      end
+
+      def test_adapters
+        assert_equal ActiveModel::Serializer::Adapter.adapters.sort, [
+          'flatten_json'.freeze,
+          'json'.freeze,
+          'json_api'.freeze,
+          'null'.freeze
+        ]
+      end
+
+      def test_lookup_adapter_by_string_name
+        assert_equal ActiveModel::Serializer::Adapter.lookup('json'.freeze), ActiveModel::Serializer::Adapter::Json
+      end
+
+      def test_lookup_adapter_by_symbol_name
+        assert_equal ActiveModel::Serializer::Adapter.lookup(:json), ActiveModel::Serializer::Adapter::Json
+      end
+
+      def test_lookup_adapter_by_class
+        klass = ActiveModel::Serializer::Adapter::Json
+        assert_equal ActiveModel::Serializer::Adapter.lookup(klass), klass
+      end
+
+      def test_lookup_adapter_from_environment_registers_adapter
+        ActiveModel::Serializer::Adapter.const_set(:AdapterFromEnvironment, Class.new)
+        klass = ::ActiveModel::Serializer::Adapter::AdapterFromEnvironment
+        name = 'adapter_from_environment'.freeze
+        assert_equal ActiveModel::Serializer::Adapter.lookup(name), klass
+        assert ActiveModel::Serializer::Adapter.adapters.include?(name)
+      ensure
+        ActiveModel::Serializer::Adapter.adapter_map.delete(name)
+        ActiveModel::Serializer::Adapter.send(:remove_const, :AdapterFromEnvironment)
+      end
+
+      def test_lookup_adapter_for_unknown_name
+        assert_raises UnknownAdapterError do
+          ActiveModel::Serializer::Adapter.lookup(:json_simple)
+        end
+      end
+
+      def test_adapter
+        assert_equal ActiveModel::Serializer.config.adapter, :flatten_json
+        assert_equal ActiveModel::Serializer.adapter, ActiveModel::Serializer::Adapter::FlattenJson
+      end
+
+      def test_register_adapter
+        new_adapter_name  = :foo
+        new_adapter_klass = Class.new
+        ActiveModel::Serializer::Adapter.register(new_adapter_name, new_adapter_klass)
+        assert ActiveModel::Serializer::Adapter.adapters.include?('foo'.freeze)
+        assert ActiveModel::Serializer::Adapter.lookup(:foo), new_adapter_klass
+      ensure
+        ActiveModel::Serializer::Adapter.adapter_map.delete(new_adapter_name.to_s)
+      end
+
+      def test_inherited_adapter_hooks_register_adapter
+        Object.const_set(:MyAdapter, Class.new)
+        my_adapter = MyAdapter
+        ActiveModel::Serializer::Adapter.inherited(my_adapter)
+        assert_equal ActiveModel::Serializer::Adapter.lookup(:my_adapter), my_adapter
+      ensure
+        ActiveModel::Serializer::Adapter.adapter_map.delete('my_adapter'.freeze)
+        Object.send(:remove_const, :MyAdapter)
+      end
+
+      def test_inherited_adapter_hooks_register_demodulized_adapter
+        Object.const_set(:MyNamespace, Module.new)
+        MyNamespace.const_set(:MyAdapter, Class.new)
+        my_adapter = MyNamespace::MyAdapter
+        ActiveModel::Serializer::Adapter.inherited(my_adapter)
+        assert_equal ActiveModel::Serializer::Adapter.lookup(:my_adapter), my_adapter
+      ensure
+        ActiveModel::Serializer::Adapter.adapter_map.delete('my_adapter'.freeze)
+        MyNamespace.send(:remove_const, :MyAdapter)
+        Object.send(:remove_const, :MyNamespace)
+      end
+
+      def test_inherited_adapter_hooks_register_subclass_of_registered_adapter
+        Object.const_set(:MyAdapter, Class.new)
+        my_adapter = MyAdapter
+        Object.const_set(:MySubclassedAdapter, Class.new(MyAdapter))
+        my_subclassed_adapter = MySubclassedAdapter
+        ActiveModel::Serializer::Adapter.inherited(my_adapter)
+        ActiveModel::Serializer::Adapter.inherited(my_subclassed_adapter)
+        assert_equal ActiveModel::Serializer::Adapter.lookup(:my_adapter), my_adapter
+        assert_equal ActiveModel::Serializer::Adapter.lookup(:my_subclassed_adapter), my_subclassed_adapter
+      ensure
+        ActiveModel::Serializer::Adapter.adapter_map.delete('my_adapter'.freeze)
+        ActiveModel::Serializer::Adapter.adapter_map.delete('my_subclassed_adapter'.freeze)
+        Object.send(:remove_const, :MyAdapter)
+        Object.send(:remove_const, :MySubclassedAdapter)
+      end
    end
  end
 end