Hack Minitest to make it less dependent on at_exit

test/test_helper.rb

@@ -20,27 +20,35 @@ require 'active_support/json'
 require 'fileutils'
 FileUtils.mkdir_p(File.expand_path('../../tmp/cache', __FILE__))
 
+# https://github.com/seattlerb/minitest/blob/master/lib/minitest/autorun.rb
 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/unit'
+  require 'minitest/spec'
+  require 'minitest/mock'
+  $minitest_version = 4
   # Minitest 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
+  minitest_run = ->(argv) { MiniTest::Unit.new.run(argv) }
+else
+  # Minitest 5
+  $minitest_version = 5
+  # 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
+  require 'minitest/spec'
+  require 'minitest/mock'
+  minitest_run = ->(argv) { Minitest.run(argv) }
 end
+require 'minitest/reporters'
+Minitest::Reporters.use!
 
 # If there's no failure info, try disabling capturing stderr:
 # `env CAPTURE_STDERR=false rake`
@@ -48,7 +56,7 @@ end
 # for 4.x and 5.x.
 if ENV['CAPTURE_STDERR'] !~ /false|1/i
   require 'capture_warnings'
-  CaptureWarnings.new(_fail_build = true).execute!
+  minitest_run = CaptureWarnings.new(_fail_build = true).execute!(minitest_run)
 else
   $VERBOSE = true
 end
@@ -71,6 +79,45 @@ 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
+
+# From:
+# https://github.com/seattlerb/minitest/blob/644a52fd0/lib/minitest/unit.rb#L768-L787
+# https://github.com/seattlerb/minitest/blob/e21fdda9d/lib/minitest.rb#L45-L59
+# But we've replaced `at_exit` with `END` called before the 'at_exit' hook.
+class MiniTestHack
+  def self.autorun(minitest_run)
+    # don't run if there was a non-exit exception
+    return if $! and not ($!.kind_of? SystemExit and $!.success?)
+
+    # Original Comment:
+    # the order here is important. The at_exit handler must be
+    # installed before anyone else gets a chance to install their
+    # own, that way we can be assured that our exit will be last
+    # to run (at_exit stacks).
+    #
+    # Now:
+    # The after_run blocks now only run on SigEXIT, which is fine.
+    exit_code = nil
+
+    trap('EXIT') do
+      if $minitest_version == 5
+        @@after_run.reverse_each(&:call)
+      else
+        @@after_tests.reverse_each(&:call)
+      end
+
+      exit exit_code || false
+    end
+
+    exit_code = minitest_run.call(ARGV)
+  end
+end
+# Run MiniTest in `END`, so that it finishes before `at_exit` fires,
+# which guarantees we can run code after MiniTest finishes
+# via an `at_exit` block.
+# This is in service of silencing non-app warnings during test run,
+# and leaves us with the warnings in our app.
+END { MiniTestHack.autorun(minitest_run) }