ar/connection_pool: honor overriden rack.test in middleware

Honoring an overidden `rack.test` allows testing closed connection between
multiple requests. This is useful if you're working on database resiliency, to
ensure the connection is in the expected state from one request to another on
the same worker.

activerecord/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Honor overridden `rack.test` in Rack environment for the connection
+    management middlware.
+
+    *Simon Eskildsen*
+
 *   Add a truncate method to the connection.
 
     *Aaron Patterson*

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -640,7 +640,7 @@ def initialize(app)
       end
 
       def call(env)
-        testing = env.key?('rack.test')
+        testing = env['rack.test']
 
         response = @app.call(env)
         response[2] = ::Rack::BodyProxy.new(response[2]) do

activerecord/test/cases/connection_management_test.rb

@@ -96,6 +96,14 @@ def test_connections_not_closed_if_exception_and_test
         assert ActiveRecord::Base.connection_handler.active_connections?
       end
 
+      def test_connections_closed_if_exception_and_explicitly_not_test
+        @env['rack.test'] = false
+        app       = Class.new(App) { def call(env); raise NotImplementedError; end }.new
+        explosive = ConnectionManagement.new(app)
+        assert_raises(NotImplementedError) { explosive.call(@env) }
+        assert !ActiveRecord::Base.connection_handler.active_connections?
+      end
+
       test "doesn't clear active connections when running in a test case" do
         @env['rack.test'] = true
         @management.call(@env)