1. An image-forming system comprising: a plurality of image-forming devices connected to a network, each image-forming device being configured to selectively perform a test print process to form a test image and an image print process to form an image based on image data, each image-forming device being configured to be set to an execution condition that defines a condition that, when satisfied by an image-forming device, indicates that the test print process should be executed by that image-forming device; and a server connected to the plurality of image-forming devices via the network, the server comprising: a detecting unit that is configured to detect a number of image-forming devices from among the plurality of image-forming devices that currently are running; an acquiring unit that is configured to acquire the execution condition of the number of image-forming devices detected by the detecting unit; and a setting unit that is configured to: determine the execution condition of each of the number of image-forming devices detected by the detecting unit, and when the number of image-forming devices detected by the detecting unit is greater than previously detected by the detecting unit, change the execution condition of a particular image-forming device to an execution condition that is different from an execution condition of an other image-forming device so that at least the particular image-forming device and the other image-forming device are set to different execution conditions, wherein each of the plurality of image-forming devices is configured to: determine whether the execution condition of that image-forming device is satisfied, and perform the test print process when it is determined that the execution condition of that image-forming device is satisfied.