1. Crankshaft testing method for the classification testing of at least one bearing surface of a crankshaft, wherein: a) a reflection of a reference line pattern at the bearing surface to be tested (reflection image) is detected by at least one sensor, using a sensor system, the reference line pattern having a plurality of lines which are spaced apart from one another, and the reference line pattern is imaged over the at least one bearing surface, the reference line pattern being imaged over the at least one bearing surface of the crankshaft to be examined in such a way that the lines extend, at least approximately, in the circumferential direction of the bearing surface, b) the detected reflection image is evaluated with regard to its contrast, and c) the crankshaft is classified as “unsatisfactory” when the contrast is below one of a predefined and a predefinable threshold value.