A method of performing a functional test of at least one embedded sub-element of a wind turbine, the wind turbine being controlled by a control algorithm of a wind turbine controller, includes the steps of: executing a predefined event pattern activating at least one sub-element of the wind turbine, obtaining measure data on the basis of measurements of at least one sub-element according to the predefined event pattern, and relating the measure data to predefined reference data and establishing a test result indicating the condition of the embedded sub-element on the basis thereof. The predefined event pattern is executed by a test algorithm overriding the control algorithm of the wind turbine controller at least partly. It is a very advantageous feature according to the present invention that the sub-elements may be tested while being embedded in the wind turbine.