Clean up AR's isolated test runner

activerecord/Rakefile

@@ -80,9 +80,19 @@ end
 
         require "bundler/setup" unless defined?(Bundler)
 
-        # Every test file loads this first, so doing it post-fork gains
-        # us nothing.
-        require "cases/helper"
+        # Every test file loads "cases/helper" first, so doing it
+        # post-fork gains us nothing.
+
+        # We need to dance around minitest autorun, though.
+        require "minitest"
+        Minitest.instance_eval do
+          alias _original_autorun autorun
+          def autorun
+            # no-op
+          end
+          require "cases/helper"
+          alias autorun _original_autorun
+        end
 
         failing_files = []
 
@@ -115,6 +125,8 @@ end
             ARGV.clear.concat test_options
             Rake.application = nil
 
+            Minitest.autorun
+
             load file
           }
 

activerecord/test/cases/unconnected_test.rb

@@ -11,6 +11,12 @@ class TestUnconnectedAdapter < ActiveRecord::TestCase
   def setup
     @underlying = ActiveRecord::Base.connection
     @specification = ActiveRecord::Base.remove_connection
+
+    # Clear out connection info from other pids (like a fork parent) too
+    pool_map = ActiveRecord::Base.connection_handler.instance_variable_get(:@owner_to_pool)
+    (pool_map.keys - [Process.pid]).each do |other_pid|
+      pool_map.delete(other_pid)
+    end
   end
 
   teardown do