In order to check the extent of coverage before the laptop roams to an access point (AP) that is different from a target AP, try one of these options:
Temporarily change the service set identifier (SSID) either on the target AP or on the surrounding APs. You can also disable the radios of the surrounding APs when the site survey is performed. Apart from this, there is no way to restrict the client from roaming into another AP.
Add a test SSID on the target AP and remove it once the site survey is done. This brings down the interface on the target AP, but only for a short while when the new SSID is configured.
Release notes / product overview / data sheet / FAQ
Technical product specification / features
WLAN adapters (wireless card) / ACU (Aironet Client Utility)