Disclosed is a testing apparatus for an outer housing of a pump, wherein the testing apparatus includes a separation element; a first and a second closure element, wherein the first and second closure element respectively close an axial end of the outer housing in a sealing manner; a middle pressure line which is arranged in the first or the second closure element; and a bounding element, wherein the bounding element closes the outlet outside of the outer housing, and wherein a high pressure line is arranged in the bounding element. The separation element is configured and arranged in the outer housing such that the separation element bounds the outlet of the outer housing and the outer housing is divided into a first pressure region and a second pressure region, wherein the first pressure region and the second pressure region are configured as pressure regions independent from one another.