Method and device for supporting generation of scenarios for testing autonomous driving and/or advanced driver assistance system, AD/ADAS, functionality for real world vehicles. A device (101; 500) provides (301) a virtual environment (200) simulating an environment relevant for operation of vehicles having said AD/ADAS functionality and in which is operating: fully computer controlled movable virtual objects (230a-c), human controlled movable virtual objects (220) and at least one virtual AD/ADAS vehicle (210) operating according to said AD/ADAS functionality. The device allows (303) a user of the device (101; 500) to, via user interface (506), control said one or more human controlled movable virtual objects (220) during operation and thereby cause generation of scenarios that the virtual AD/ADAS vehicle (210) is subjected to.