Merge pull request rails#41884 from jhawthorn/null_pool_methods

Add more methods to NullPool

Author: jhawthorn

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

@@ -26,9 +26,10 @@ class NullPool # :nodoc:
 
       attr_accessor :schema_cache
 
-      def connection_klass
-        nil
-      end
+      def connection_klass; end
+      def checkin(_); end
+      def remove(_); end
+      def async_executor; end
     end
 
     # Connection pool base class for managing Active Record database

activerecord/test/cases/connection_adapters/standalone_connection_test.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+require "support/connection_helper"
+
+module ActiveRecord
+  module ConnectionAdapters
+    class StandaloneConnectionTest < ActiveRecord::TestCase
+      def setup
+        super
+
+        db_config = ActiveRecord::Base.configurations.configs_for(env_name: "arunit", name: "primary")
+        @connection = ActiveRecord::Base.public_send(db_config.adapter_method, db_config.configuration_hash)
+      end
+
+      def test_can_query
+        result = @connection.select_all("SELECT 1")
+        assert_equal [[1]], result.rows
+      end
+
+      def test_silently_ignore_async
+        result = @connection.select_all("SELECT 1", async: true)
+        assert_equal [[1]], result.rows
+      end
+
+      def test_can_throw_away
+        @connection.throw_away!
+        assert_not @connection.active?
+      end
+
+      def test_can_close
+        @connection.close
+      end
+    end
+  end
+end