1. A method for testing an application in a virtual computer system, the virtual computer system including hardware including a CPU and a memory, first and second virtual machines each having a program operating on the CPU, and a virtual computer monitor configured to control the first and second virtual machines, the method comprising: transmitting a request to select one of first and second conditions of a test of the application from the first virtual machine configured to execute the test of the application to the second virtual machine configured to control the virtual computer system via the virtual computer monitor; generating, when the virtual machine monitor receives the request to select the one of the first and second conditions of the test of the application, a clone of the first virtual machine by the virtual machine monitor; and executing the test of the application based on the first condition in the first virtual machine while executing the test of the application based on the second condition in the generated clone of the first virtual machine.