Various over-the-air (OTA) testing environments are presented, focusing on their capability to produce single- or multi-directional channels, i.e., producing a single path or multipath components. The OTA systems are discussed in terms of the chambers used, either anechoic, reverberation, or hybrid, and the capabilities to produce different channels. It is suggested that future developments in OTA testing technology will require the development of smart testing environments that can accommodate the diverse increasing demands of emerging applications.