diff --git a/.rubocop.yml b/.rubocop.yml
index db25cbf5..f31d8344 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -58,3 +58,29 @@ Style/MultilineOperationIndentation:
 Style/BlockDelimiters:
   Enabled: true
   EnforcedStyle: line_count_based
+
+########## test_helper.rb sanity
+Style/EndBlock:
+  Exclude:
+    - test/test_helper.rb
+
+Style/SpecialGlobalVars:
+  Exclude:
+    - test/test_helper.rb
+
+Style/GlobalVars:
+  Exclude:
+    - test/test_helper.rb
+
+Style/AndOr:
+  Exclude:
+    - test/test_helper.rb
+    - 'lib/active_model/serializer/lint.rb'
+
+Style/Not:
+  Exclude:
+    - test/test_helper.rb
+
+Style/ClassCheck:
+  Exclude:
+    - test/test_helper.rb
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index c9a58846..c9c8e604 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -53,13 +53,6 @@ Style/AlignHash:
   Exclude:
     - 'test/action_controller/json_api/pagination_test.rb'
 
-# Offense count: 1
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle, SupportedStyles.
-Style/AndOr:
-  Exclude:
-    - 'lib/active_model/serializer/lint.rb'
-
 # Offense count: 25
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle, SupportedStyles.
@@ -105,7 +98,6 @@ Style/EachWithObject:
 Style/GuardClause:
   Exclude:
     - 'lib/active_model/serializer.rb'
-    - 'test/capture_warnings.rb'
 
 # Offense count: 12
 # Cop supports --auto-correct.
diff --git a/.simplecov b/.simplecov
index ce914ce6..616df804 100644
--- a/.simplecov
+++ b/.simplecov
@@ -41,6 +41,7 @@ SimpleCov.profiles.define 'app' do
   add_filter '/config/'
   add_filter '/db/'
   add_filter 'tasks'
+  add_filter '/.bundle/'
 end
 
 ## START TRACKING COVERAGE (before activating SimpleCov)
diff --git a/.travis.yml b/.travis.yml
index 6db23056..422e849d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,7 +16,7 @@ cache:
     - vendor/bundle
 
 script:
-  - env CAPTURE_STDERR=${CAPTURE_STDERR:-false} bundle exec rake ci
+  - bundle exec rake ci
 
 env:
   - "RAILS_VERSION=4.0"
@@ -31,8 +31,6 @@ matrix:
   - rvm: 2.1
     env: RAILS_VERSION=master
   include:
-  - rvm: 2.2
-    env: CAPTURE_STDERR=true
   - rvm: jruby-9.0.4.0
     env: JRUBY_OPTS='-Xcompat.version=2.0 --server -Xcompile.invokedynamic=false -Xcli.debug=true --debug'
   allow_failures:
diff --git a/test/capture_warnings.rb b/test/capture_warnings.rb
deleted file mode 100644
index d3674cab..00000000
--- a/test/capture_warnings.rb
+++ /dev/null
@@ -1,75 +0,0 @@
-# https://raw.githubusercontent.com/metric_fu/metric_fu/master/spec/capture_warnings.rb
-require 'tempfile'
-require 'fileutils'
-
-class CaptureWarnings
-  def initialize(fail_on_warnings = true)
-    @fail_on_warnings = fail_on_warnings
-    @stderr_file = Tempfile.new('app.stderr')
-    @app_root ||= Dir.pwd
-    @output_dir = File.join(app_root, 'tmp')
-    FileUtils.mkdir_p(output_dir)
-    @ignore_dirs = [
-      File.join(app_root, '.bundle'),
-      File.join(app_root, 'bundle'),
-      File.join(app_root, 'vendor')
-    ]
-    @output = STDOUT
-  end
-
-  def execute!
-    $VERBOSE = true
-    $stderr.reopen(stderr_file.path)
-
-    Minitest.after_run do
-      stderr_file.rewind
-      lines = stderr_file.read.split("\n")
-      stderr_file.close!
-      $stderr.reopen(STDERR)
-      after_tests(lines)
-    end
-  end
-
-  def after_tests(lines)
-    app_warnings, other_warnings = lines.partition do |line|
-      line.include?(app_root) && ignore_dirs.none? { |ignore_dir| line.include?(ignore_dir) }
-    end
-
-    if app_warnings.any?
-      warnings_message = app_warnings.join("\n")
-      print_warnings = true
-    else
-      warnings_message = 'None. Yay!'
-      ENV['FULL_BUILD'] ||= ENV['CI']
-      running_ci          = ENV['FULL_BUILD'] =~ /\Atrue\z/i
-      print_warnings = running_ci
-    end
-
-    if other_warnings.any?
-      File.write(File.join(output_dir, 'warnings.txt'), other_warnings.join("\n") << "\n")
-      warnings_message << "\nNon-app warnings written to tmp/warnings.txt"
-      print_warnings = true
-    end
-
-    header = "#{'-' * 22} app warnings: #{'-' * 22}"
-    message = <<-EOF.strip_heredoc
-
-    #{header}
-
-    #{warnings_message}
-
-    #{'-' * header.size}
-    EOF
-
-    output.puts(message) if print_warnings
-
-    # fail the build...
-    if fail_on_warnings && app_warnings.any?
-      abort "Failing build due to app warnings: #{app_warnings.inspect}"
-    end
-  end
-
-  private
-
-  attr_reader :stderr_file, :app_root, :output_dir, :ignore_dirs, :fail_on_warnings, :output
-end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 9d069820..809f3ca4 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -21,37 +21,26 @@ require 'fileutils'
 FileUtils.mkdir_p(File.expand_path('../../tmp/cache', __FILE__))
 
 gem 'minitest'
-require 'minitest/autorun'
-require 'minitest/reporters'
-Minitest::Reporters.use!
-if defined?(Minitest::Test)
-  $minitest_version = 5 # rubocop:disable Style/GlobalVars
-  # Minitest 5
-  # https://github.com/seattlerb/minitest/blob/e21fdda9d/lib/minitest/autorun.rb
-  # https://github.com/seattlerb/minitest/blob/e21fdda9d/lib/minitest.rb#L45-L59
-else
-  $minitest_version = 4 # rubocop:disable Style/GlobalVars
+begin
+  require 'minitest'
+rescue LoadError
   # Minitest 4
+  require 'minitest/autorun'
+  $minitest_version = 4
   # https://github.com/seattlerb/minitest/blob/644a52fd0/lib/minitest/autorun.rb
   # https://github.com/seattlerb/minitest/blob/644a52fd0/lib/minitest/unit.rb#L768-L787
   # Ensure backward compatibility with Minitest 4
   Minitest = MiniTest unless defined?(Minitest)
   Minitest::Test = MiniTest::Unit::TestCase
-  def Minitest.after_run(&block)
-    MiniTest::Unit.after_tests(&block)
-  end
-end
-
-# If there's no failure info, try disabling capturing stderr:
-# `env CAPTURE_STDERR=false rake`
-# This is way easier than writing a Minitest plugin
-# for 4.x and 5.x.
-if ENV['CAPTURE_STDERR'] !~ /false|1/i
-  require 'capture_warnings'
-  CaptureWarnings.new(_fail_build = true).execute!
 else
-  $VERBOSE = true
+  # Minitest 5
+  require 'minitest/autorun'
+  $minitest_version = 5
+  # https://github.com/seattlerb/minitest/blob/e21fdda9d/lib/minitest/autorun.rb
+  # https://github.com/seattlerb/minitest/blob/e21fdda9d/lib/minitest.rb#L45-L59
 end
+require 'minitest/reporters'
+Minitest::Reporters.use!
 
 require 'active_model_serializers'
 require 'active_model/serializer/railtie'
@@ -71,6 +60,6 @@ require 'fixtures/active_record'
 require 'fixtures/poro'
 
 ActiveSupport.on_load(:active_model_serializers) do
-  $action_controller_logger = ActiveModelSerializers.logger # rubocop:disable Style/GlobalVars
+  $action_controller_logger = ActiveModelSerializers.logger
   ActiveModelSerializers.logger = Logger.new(IO::NULL)
 end