A test support program to effectively and reliably check performance of functions which operate with other unspecified servers. A pair of a request message and a response message is stored as a message log. When a processing function based on a program under development being checked outputs a test request message, a computer selects a message log appropriate to the test request message as a template message under preset selection rules. The computer creates a test response message by editing the response message of the selected template message under preset editing rules. Then the computer sends the created test response message as a response to the test request message.