Improve adapter test coverage per groyoh

docs/rfcs/0000-namespace.md

@@ -70,7 +70,7 @@ at the first moment.
 ## Renaming of class and modules
 
 When moving some content to the new namespace we can find some names that does
-not make much sense like `ActiveModelSerializers::Adapter::JsonApi`.
+not make much sense like `ActiveModel::Serializer::Adapter::JsonApi`.
 Discussion of renaming existing classes / modules and JsonApi objects will
 happen in separate pull requests, and issues, and in the google doc
 https://docs.google.com/document/d/1rcrJr0sVcazY2Opd_6Kmv1iIwuHbI84s1P_NzFn-05c/edit?usp=sharing

lib/active_model/serializer.rb

@@ -23,8 +23,6 @@ module ActiveModel
     include Links
     include Meta
     include Type
-    # Deprecated
-    require 'active_model_serializers/adapter'
 
     # @param resource [ActiveRecord::Base, ActiveModelSerializers::Model]
     # @return [ActiveModel::Serializer]

lib/active_model_serializers.rb

@@ -9,6 +9,7 @@ module ActiveModelSerializers
   autoload :Deserialization
   autoload :Logging
   autoload :Test
+  autoload :Adapter
 
   class << self; attr_accessor :logger; end
   self.logger = ActiveSupport::TaggedLogging.new(ActiveSupport::Logger.new(STDOUT))

test/active_model_serializers/adapter_for_test.rb

@@ -10,6 +10,12 @@ module ActiveModelSerializers
       ActiveModelSerializers.config.adapter = @previous_adapter
     end
 
+    def test_serializer_adapter_returns_configured__adapter
+      assert_output(nil, /ActiveModelSerializers::configured_adapter/) do
+        assert_equal ActiveModelSerializers::Adapter.configured_adapter, ActiveModel::Serializer.adapter
+      end
+    end
+
     def test_returns_default_adapter
       adapter = ActiveModelSerializers::Adapter.configured_adapter
       assert_equal ActiveModelSerializers::Adapter::Attributes, adapter
@@ -24,11 +30,40 @@ module ActiveModelSerializers
       ActiveModelSerializers.config.adapter = @previous_adapter
     end
 
+    def test_overwrite_adapter_with_camelcased_symbol
+      ActiveModelSerializers.config.adapter = :JsonApi
+
+      adapter = ActiveModelSerializers::Adapter.configured_adapter
+      assert_equal ActiveModelSerializers::Adapter::JsonApi, adapter
+    ensure
+      ActiveModelSerializers.config.adapter = @previous_adapter
+    end
+
+    def test_overwrite_adapter_with_string
+      ActiveModelSerializers.config.adapter = 'json_api'
+
+      adapter = ActiveModelSerializers::Adapter.configured_adapter
+      assert_equal ActiveModelSerializers::Adapter::JsonApi, adapter
+    ensure
+      ActiveModelSerializers.config.adapter = @previous_adapter
+    end
+
+    def test_overwrite_adapter_with_a_camelcased_string
+      ActiveModelSerializers.config.adapter = 'JsonApi'
+
+      adapter = ActiveModelSerializers::Adapter.configured_adapter
+      assert_equal ActiveModelSerializers::Adapter::JsonApi, adapter
+    ensure
+      ActiveModelSerializers.config.adapter = @previous_adapter
+    end
+
     def test_overwrite_adapter_with_class
       ActiveModelSerializers.config.adapter = ActiveModelSerializers::Adapter::Null
 
       adapter = ActiveModelSerializers::Adapter.configured_adapter
       assert_equal ActiveModelSerializers::Adapter::Null, adapter
+    ensure
+      ActiveModelSerializers.config.adapter = @previous_adapter
     end
 
     def test_raises_exception_if_invalid_symbol_given
@@ -37,6 +72,8 @@ module ActiveModelSerializers
       assert_raises UnknownAdapterError do
         ActiveModelSerializers::Adapter.configured_adapter
       end
+    ensure
+      ActiveModelSerializers.config.adapter = @previous_adapter
     end
 
     def test_raises_exception_if_it_does_not_know_hot_to_infer_adapter
@@ -45,6 +82,8 @@ module ActiveModelSerializers
       assert_raises UnknownAdapterError do
         ActiveModelSerializers::Adapter.configured_adapter
       end
+    ensure
+      ActiveModelSerializers.config.adapter = @previous_adapter
     end
 
     def test_adapter_class_for_known_adapter