Move Adapter.adapter_for to Serializer.adapter

test/serializers/adapter_for_test.rb

@@ -0,0 +1,50 @@
+module ActiveModel
+  class Serializer
+    class AdapterForTest < Minitest::Test
+      def setup
+        @previous_adapter = ActiveModel::Serializer.config.adapter
+      end
+
+      def teardown
+        ActiveModel::Serializer.config.adapter = @previous_adapter
+      end
+
+      def test_returns_default_adapter
+        adapter = ActiveModel::Serializer.adapter
+        assert_equal ActiveModel::Serializer::Adapter::SimpleAdapter, adapter
+      end
+
+      def test_overwrite_adapter_with_symbol
+        ActiveModel::Serializer.config.adapter = :null
+
+        adapter = ActiveModel::Serializer.adapter
+        assert_equal ActiveModel::Serializer::Adapter::NullAdapter, adapter
+      ensure
+
+      end
+
+      def test_overwrite_adapter_with_class
+        ActiveModel::Serializer.config.adapter = ActiveModel::Serializer::Adapter::NullAdapter
+
+        adapter = ActiveModel::Serializer.adapter
+        assert_equal ActiveModel::Serializer::Adapter::NullAdapter, adapter
+      end
+
+      def test_raises_exception_if_invalid_symbol_given
+        ActiveModel::Serializer.config.adapter = :unknown
+
+        assert_raises ArgumentError do
+          ActiveModel::Serializer.adapter
+        end
+      end
+
+      def test_raises_exception_if_it_does_not_know_hot_to_infer_adapter
+        ActiveModel::Serializer.config.adapter = 42
+
+        assert_raises ArgumentError do
+          ActiveModel::Serializer.adapter
+        end
+      end
+    end
+  end
+end