diff --git a/lib/active_model/serializable_resource.rb b/lib/active_model/serializable_resource.rb
index fa3fbe035..aa8f139a2 100644
--- a/lib/active_model/serializable_resource.rb
+++ b/lib/active_model/serializable_resource.rb
@@ -1,4 +1,4 @@
-require "set"
+require 'set'
 module ActiveModel
   class SerializableResource
 
@@ -76,7 +76,9 @@ def serializer?
 
     private
 
+    ActiveModelSerializers.silence_warnings do
     attr_reader :resource, :adapter_opts, :serializer_opts
+    end
 
   end
 end
diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index 738743007..2c56dd2be 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -9,6 +9,7 @@ class Serializer
     autoload :Adapter
     autoload :Lint
     autoload :Associations
+    autoload :Fieldset
     include Configuration
     include Associations
 
@@ -51,10 +52,10 @@ def self.attribute(attr, options = {})
       @_attributes_keys[attr] = { key: key } if key != attr
       @_attributes << key unless @_attributes.include?(key)
 
-      unless respond_to?(key, false) || _fragmented.respond_to?(attr)
+      ActiveModelSerializers.silence_warnings do
         define_method key do
           object.read_attribute_for_serialization(attr)
-        end
+        end unless respond_to?(key, false) || _fragmented.respond_to?(attr)
       end
     end
 
diff --git a/lib/active_model/serializer/adapter.rb b/lib/active_model/serializer/adapter.rb
index 0b8118d60..afa4fea1e 100644
--- a/lib/active_model/serializer/adapter.rb
+++ b/lib/active_model/serializer/adapter.rb
@@ -1,13 +1,25 @@
-require 'active_model/serializer/adapter/fragment_cache'
-
 module ActiveModel
   class Serializer
     class Adapter
       extend ActiveSupport::Autoload
-      autoload :Json
+      require 'active_model/serializer/adapter/json'
+      require 'active_model/serializer/adapter/json_api'
       autoload :FlattenJson
       autoload :Null
-      autoload :JsonApi
+      autoload :FragmentCache
+
+      def self.create(resource, options = {})
+        override = options.delete(:adapter)
+        klass = override ? adapter_class(override) : ActiveModel::Serializer.adapter
+        klass.new(resource, options)
+      end
+
+      def self.adapter_class(adapter)
+        adapter_name = adapter.to_s.classify.sub("API", "Api")
+        "ActiveModel::Serializer::Adapter::#{adapter_name}".safe_constantize
+      end
+
+      ##### AbstractAdapter
 
       attr_reader :serializer
 
@@ -26,17 +38,6 @@ def as_json(options = nil)
         hash
       end
 
-      def self.create(resource, options = {})
-        override = options.delete(:adapter)
-        klass = override ? adapter_class(override) : ActiveModel::Serializer.adapter
-        klass.new(resource, options)
-      end
-
-      def self.adapter_class(adapter)
-        adapter_name = adapter.to_s.classify.sub("API", "Api")
-        "ActiveModel::Serializer::Adapter::#{adapter_name}".safe_constantize
-      end
-
       def fragment_cache(*args)
         raise NotImplementedError, 'This is an abstract method. Should be implemented at the concrete adapter.'
       end
@@ -94,6 +95,7 @@ def include_meta(json)
         json[meta_key] = meta if meta
         json
       end
+      ##### AbstractAdapter
     end
   end
 end
diff --git a/lib/active_model/serializer/adapter/json/fragment_cache.rb b/lib/active_model/serializer/adapter/json/fragment_cache.rb
index 761a6e548..0d01b87a2 100644
--- a/lib/active_model/serializer/adapter/json/fragment_cache.rb
+++ b/lib/active_model/serializer/adapter/json/fragment_cache.rb
@@ -1,3 +1,4 @@
+require 'active_model/serializer/adapter/fragment_cache'
 module ActiveModel
   class Serializer
     class Adapter
@@ -12,4 +13,4 @@ def fragment_cache(cached_hash, non_cached_hash)
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/active_model/serializer/adapter/json_api/fragment_cache.rb b/lib/active_model/serializer/adapter/json_api/fragment_cache.rb
index 6ce1c1848..d266801fe 100644
--- a/lib/active_model/serializer/adapter/json_api/fragment_cache.rb
+++ b/lib/active_model/serializer/adapter/json_api/fragment_cache.rb
@@ -1,3 +1,4 @@
+require 'active_model/serializer/adapter/fragment_cache'
 module ActiveModel
   class Serializer
     class Adapter
@@ -20,4 +21,4 @@ def fragment_cache(root, cached_hash, non_cached_hash)
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/active_model/serializer/associations.rb b/lib/active_model/serializer/associations.rb
index f864a0f0a..1320eae3e 100644
--- a/lib/active_model/serializer/associations.rb
+++ b/lib/active_model/serializer/associations.rb
@@ -73,11 +73,9 @@ def has_one(name, options = {})
         def associate(reflection)
           self._reflections = _reflections.dup
 
-          unless method_defined?(reflection.name)
-            define_method reflection.name do
-              object.send reflection.name
-            end
-          end
+          define_method reflection.name do
+            object.send reflection.name
+          end unless method_defined?(reflection.name)
 
           self._reflections << reflection
         end
diff --git a/lib/active_model/serializer/fieldset.rb b/lib/active_model/serializer/fieldset.rb
index 3ff42bedd..63333cf27 100644
--- a/lib/active_model/serializer/fieldset.rb
+++ b/lib/active_model/serializer/fieldset.rb
@@ -18,7 +18,9 @@ def fields_for(serializer)
 
     private
 
+      ActiveModelSerializers.silence_warnings do
       attr_reader :raw_fields, :root
+      end
 
       def parsed_fields
         if raw_fields.is_a?(Hash)
@@ -37,4 +39,4 @@ def parsed_fields
 
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/active_model_serializers.rb b/lib/active_model_serializers.rb
index 211a2870e..01c23e5f7 100644
--- a/lib/active_model_serializers.rb
+++ b/lib/active_model_serializers.rb
@@ -1,7 +1,18 @@
+module ActiveModelSerializers
+  module_function
+
+  def silence_warnings
+    verbose = $VERBOSE
+    $VERBOSE = nil
+    yield
+  ensure
+    $VERBOSE = verbose
+  end
+
+end
 require 'active_model'
 require 'active_model/serializer/version'
 require 'active_model/serializer'
-require 'active_model/serializer/fieldset'
 require 'active_model/serializable_resource'
 
 begin
diff --git a/test/action_controller/serialization_scope_name_test.rb b/test/action_controller/serialization_scope_name_test.rb
index 2af0a1fa9..6e2b15e6e 100644
--- a/test/action_controller/serialization_scope_name_test.rb
+++ b/test/action_controller/serialization_scope_name_test.rb
@@ -4,8 +4,10 @@
 class DefaultScopeNameTest < ActionController::TestCase
   class UserSerializer < ActiveModel::Serializer
     attributes :admin?
-    def admin?
-      current_user.admin
+    ActiveModelSerializers.silence_warnings do
+      def admin?
+        current_user.admin
+      end
     end
   end
 
@@ -34,8 +36,10 @@ def test_default_scope_name
 class SerializationScopeNameTest < ActionController::TestCase
   class AdminUserSerializer < ActiveModel::Serializer
     attributes :admin?
-    def admin?
-      current_admin.admin
+    ActiveModelSerializers.silence_warnings do
+      def admin?
+        current_admin.admin
+      end
     end
   end
 
@@ -60,4 +64,4 @@ def test_override_scope_name_with_controller
     get :render_new_user
     assert_equal '{"data":{"id":"1","type":"users","attributes":{"admin?":true}}}', @response.body
   end
-end
\ No newline at end of file
+end
diff --git a/test/action_controller/serialization_test.rb b/test/action_controller/serialization_test.rb
index 8c89ceac0..fab43af07 100644
--- a/test/action_controller/serialization_test.rb
+++ b/test/action_controller/serialization_test.rb
@@ -129,7 +129,6 @@ def render_fragment_changed_object_with_except_cache_enabled
         def render_fragment_changed_object_with_relationship
           comment = Comment.new({ id: 1, body: 'ZOMG A COMMENT' })
           comment2 = Comment.new({ id: 1, body: 'ZOMG AN UPDATED-BUT-NOT-CACHE-EXPIRED COMMENT' })
-          author = Author.new(id: 1, name: 'Joao Moura.')
           like = Like.new({ id: 1, likeable: comment, time: 3.days.ago })
 
           generate_cached_serializer(like)
@@ -215,14 +214,16 @@ def test_render_json_object_without_serializer
         get :render_json_object_without_serializer
 
         assert_equal 'application/json', @response.content_type
-        assert_equal ({error: 'Result is Invalid'}).to_json, @response.body
+        expected_body = {error: 'Result is Invalid'}
+        assert_equal expected_body.to_json, @response.body
       end
 
       def test_render_json_array_object_without_serializer
         get :render_json_array_object_without_serializer
 
         assert_equal 'application/json', @response.content_type
-        assert_equal ([{error: 'Result is Invalid'}]).to_json, @response.body
+        expected_body = [{error: 'Result is Invalid'}]
+        assert_equal expected_body.to_json, @response.body
       end
 
       def test_render_array_using_implicit_serializer
@@ -405,9 +406,9 @@ def use_adapter?
             false
           end
         }.new
-        assert_match /adapter: false/, (capture(:stderr) {
+        assert_match(/adapter: false/, (capture(:stderr) {
           controller.get_serializer(Profile.new)
-        })
+        }))
       end
 
       def test_dont_warn_overridding_use_adapter_as_truthy_on_controller_instance
diff --git a/test/adapter/json/belongs_to_test.rb b/test/adapter/json/belongs_to_test.rb
index a5dbfe14d..f39080fd5 100644
--- a/test/adapter/json/belongs_to_test.rb
+++ b/test/adapter/json/belongs_to_test.rb
@@ -11,7 +11,6 @@ def setup
             @comment = Comment.new(id: 1, body: 'ZOMG A COMMENT')
             @post.comments = [@comment]
             @anonymous_post.comments = []
-            @post.author = @author
             @comment.post = @post
             @comment.author = nil
             @anonymous_post.author = nil
diff --git a/test/fixtures/poro.rb b/test/fixtures/poro.rb
index 2b281049c..0c0e3a587 100644
--- a/test/fixtures/poro.rb
+++ b/test/fixtures/poro.rb
@@ -1,3 +1,5 @@
+verbose = $VERBOSE
+$VERBOSE = nil
 class Model
   FILE_DIGEST = Digest::MD5.hexdigest(File.open(__FILE__).read)
 
@@ -260,9 +262,4 @@ def maker
   cache only: [:id]
   attributes :id
 end
-
-RaiseErrorSerializer = Class.new(ActiveModel::Serializer) do
-  def json_key
-    raise StandardError, 'Intentional error for rescue_from test'
-  end
-end
+$VERBOSE = verbose
diff --git a/test/generators/serializer_generator_test.rb b/test/generators/serializer_generator_test.rb
index 815468b7b..a8e8696d9 100644
--- a/test/generators/serializer_generator_test.rb
+++ b/test/generators/serializer_generator_test.rb
@@ -46,7 +46,7 @@ def test_generates_attributes_and_associations
   def test_with_no_attributes_does_not_add_extra_space
     run_generator ["account"]
     assert_file "app/serializers/account_serializer.rb" do |content|
-      assert_no_match /\n\nend/, content
+      assert_no_match(/\n\nend/, content)
     end
   end
 end
diff --git a/test/serializers/associations_test.rb b/test/serializers/associations_test.rb
index 89afdcc67..b7b77cf95 100644
--- a/test/serializers/associations_test.rb
+++ b/test/serializers/associations_test.rb
@@ -81,7 +81,7 @@ def test_has_many_with_no_serializer
       def test_serializer_options_are_passed_into_associations_serializers
         association = @post_serializer
                         .associations
-                        .detect { |association| association.key == :comments }
+                        .detect { |assoc| assoc.key == :comments }
 
         assert association.serializer.first.custom_options[:custom_options]
       end
diff --git a/test/serializers/cache_test.rb b/test/serializers/cache_test.rb
index 60c351944..be8048538 100644
--- a/test/serializers/cache_test.rb
+++ b/test/serializers/cache_test.rb
@@ -46,13 +46,13 @@ def test_cache_key_definition
       end
 
       def test_cache_key_interpolation_with_updated_at
-        author = render_object_with_cache(@author)
+        render_object_with_cache(@author)
         assert_equal(nil, ActionController::Base.cache_store.fetch(@author.cache_key))
         assert_equal(@author_serializer.attributes.to_json, ActionController::Base.cache_store.fetch("#{@author_serializer.class._cache_key}/#{@author_serializer.object.id}-#{@author_serializer.object.updated_at.strftime("%Y%m%d%H%M%S%9N")}").to_json)
       end
 
       def test_default_cache_key_fallback
-        comment = render_object_with_cache(@comment)
+        render_object_with_cache(@comment)
         assert_equal(@comment_serializer.attributes.to_json, ActionController::Base.cache_store.fetch(@comment.cache_key).to_json)
       end
 
@@ -73,7 +73,7 @@ def test_associations_separately_cache
         assert_equal(nil, ActionController::Base.cache_store.fetch(@comment.cache_key))
 
         Timecop.freeze(Time.now) do
-          post = render_object_with_cache(@post)
+          render_object_with_cache(@post)
 
           assert_equal(@post_serializer.attributes, ActionController::Base.cache_store.fetch(@post.cache_key))
           assert_equal(@comment_serializer.attributes, ActionController::Base.cache_store.fetch(@comment.cache_key))
@@ -121,7 +121,7 @@ def test_fragment_fetch_with_virtual_associations
       end
 
       def test_uses_file_digest_in_cache_key
-        blog = render_object_with_cache(@blog)
+        render_object_with_cache(@blog)
         assert_equal(@blog_serializer.attributes, ActionController::Base.cache_store.fetch(@blog.cache_key_with_digest))
       end
 
diff --git a/test/test_helper.rb b/test/test_helper.rb
index eee2d0490..1327188e2 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -15,10 +15,17 @@
 
 
 require 'capture_warnings'
-@capture_warnings = CaptureWarnings.new(fail_build = false)
+@capture_warnings = CaptureWarnings.new(fail_build = true)
 @capture_warnings.before_tests
-Minitest.after_run do
-  @capture_warnings.after_tests
+if Minitest.respond_to?(:after_run)
+  Minitest.after_run do
+    @capture_warnings.after_tests
+  end
+else
+  at_exit do
+    STDOUT.puts "Minitest.after_run not available."
+    @capture_warnings.after_tests
+  end
 end
 
 require 'active_model_serializers'