(Reuters) – Semiconductor-testing equipment maker Teradyne forecast its first-quarter revenue below Wall Street estimates on Tuesday, hurt by lower demand for its chip-testing equipment. Shares of the company fell around 6% in extended trading. The company designs and develops technology to test chips and electronic equipment and sells robotic systems to customers in the manufacturing sector. Teradyne’s revenue has been declining year-on-year over the past few quarters as the chip-testing technology provider grapples with lower demand for its products as clients cut back on spending amid an un…