Fix test execute after disconnect, AR change of behaviour

Author: JesseChavez

test/db/mysql/simple_test.rb

@@ -447,10 +447,12 @@ def test_jdbc_error
   def test_execute_after_disconnect
     connection.disconnect!
 
-    assert_raise(ActiveRecord::ConnectionNotEstablished) do
-      connection.execute('SELECT 1')
+    # active record change of behaviour 7.1, reconnects on query execution.
+    result = assert_nothing_raised do
+      connection.execute('SELECT 1 + 2')
     end
 
+    assert_equal 3, result.rows.flatten.first
   ensure
     connection.reconnect!
   end