Use PG Connection#escape over Connection.escape

Also fix AbstractMysqlAdapterTest

activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb

@@ -43,7 +43,7 @@ def quote(value) # :nodoc:
 
         # Quotes strings for use in SQL input.
         def quote_string(s) # :nodoc:
-          PG::Connection.escape(s)
+          @connection.escape(s)
         end
 
         # Checks the following cases:

activerecord/test/cases/adapters/abstract_mysql_adapter_test.rb

@@ -3,20 +3,22 @@
 require "cases/helper"
 
 class AbstractMysqlAdapterTest < ActiveRecord::Mysql2TestCase
-  class ExampleMysqlAdapter < ActiveRecord::ConnectionAdapters::AbstractMysqlAdapter; end
+  if current_adapter?(:Mysql2Adapter)
+    class ExampleMysqlAdapter < ActiveRecord::ConnectionAdapters::AbstractMysqlAdapter; end
 
-  def setup
-    @conn = ExampleMysqlAdapter.new(
-      ActiveRecord::ConnectionAdapters::Mysql2Adapter.new_client({}),
-      ActiveRecord::Base.logger,
-      nil,
-      { socket: File::NULL }
-    )
-  end
+    def setup
+      @conn = ExampleMysqlAdapter.new(
+        ActiveRecord::ConnectionAdapters::Mysql2Adapter.new_client({}),
+        ActiveRecord::Base.logger,
+        nil,
+        { socket: File::NULL }
+      )
+    end
 
-  def test_execute_not_raising_error
-    assert_nothing_raised do
-      @conn.execute("SELECT 1")
+    def test_execute_not_raising_error
+      assert_nothing_raised do
+        @conn.execute("SELECT 1")
+      end
     end
   end
 end

activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb

@@ -38,6 +38,10 @@ def exec_params(*)
             {}
           end
 
+          def escape(query)
+            PG::Connection.escape(query)
+          end
+
           def reset
             raise PG::ConnectionBad, "I'll be rescued by the reconnect method"
           end