In this paper several recommendations and considerations on electromagnetic compatibility (EMC) testing of unmanned aerial vehicles (UAV, or drone) are presented. Currently, the standardization of drone EMC measurements is not yet fully established. These products are usually tested according to EN 55032, EN 55024, EN 64000-4-3 and EN 61000-4-8, while the scope of these standards is not UAV specific. The focus of this paper is on the testability of UAV emission and immunity from various aspects. The main goal of this paper is to initiate discussions regarding UAV specific conditions to describe measurement setups, conditions, and limitations suitable to drones. First, the UAV and the test environment shall be prepared from safety ant testability point of view. These aspects and recommended conditions - e.g., drone fastening, applying artificial load, and emulating the Earth's magnetic field - are explained in this paper. While the drones are assembled from CE certified components, the whole product requires a system level validation. The test conditions, limits, and stress levels shall be aligned to the specific environment an UAV might be exposed to. An initiative study aiming to describe the UAV exclusive electromagnetic conditions are also presented here. Additionally, several key aspects for EMC engineering of UAV's are also discussed in this paper, mainly focusing on functionality relevant EMC issues and solutions.