Abstract: The invention relates to automated testing of equipment items of the electronic, electrical, and optical type over a range of environmental conditions. A testing apparatus operates to vary an operating environment of an item of test equipment between a lower extreme and an upper extreme, and iteratively searches each test parameter for a peak response. The peak response is compared with a response limit specified in a customer specification or an international standard. The apparatus assesses a design robustness of the equipment item by comparing a set of measured responses with a maximum range of responses specified in the customer specification or international standard. The apparatus produces a data output for each performance parameter tested, identifying performance parameters which are outside the customer specification, or which have insufficient design robustness.