The work of a testing pump, such as a hydrostatic or pressure test pump, is to apply high pressure to a system to check for leaks, structural integrity, and safety. It works by filling a system like a pipeline, tank, or boiler with a liquid (usually water) and then pressurizing it to a specific level to reveal weaknesses, leaks, or manufacturing flaws that could cause failure. This process ensures that the system can safely and reliably withstand the stresses of its operational environment.