Provided is a method for testing integrity of a base for printhead integrated circuits. The base has at least one fluid inlet in fluid communication with a plurality of fluid outlets via discrete fluid paths. The method includes the steps of engaging the, or each, fluid inlet of the base to a fluid supply in a sealing manner, charging the base with pressurized fluid until a predetermined pressure is reached, and monitoring the pressure in the base for a predetermined period of time, wherein a rate of pressure decay is indicative of an integrity of the base.