A method of testing the rotor engagement of a peristaltic pump, the method comprising the steps of: a) providing a pump system comprising: a peristaltic pump rotor; a tube; a valve; a pressure sensor; a comparator; and a processor; wherein: the valve is situated on the tube downstream of the peristaltic pump rotor; and the pressure sensor is arranged to sense the fluid pressure in the tube downstream of the peristaltic pump rotor and upstream of the valve; and the peristaltic pump rotor includes at least one member having a tube contact portion; the at least one member being rotatable about a drive axis to move the tube contact portion along an arcuate path, the tube contact portion being configured to occlude the tube; b) providing a fluid in the tube; c) arranging the pump system such that the valve is open, the peristaltic pump rotor is inactive and the tube contact portion is occluding the tube; d) closing the valve; e) actuating the peristaltic pump rotor from a first rotor position to a second rotor position such that the peristaltic pump rotor is angularly displaced about the drive axis by a predetermined priming angular displacement; f) holding the peristaltic pump rotor in the second rotor position for a holding interval of predetermined duration; g) using the pressure sensor to measure maximum pressure of the fluid in the tube downstream of the peristaltic pump rotor during and/or after completing step e); h) using the pressure sensor to measure any pressure drop in the fluid in the tube downstream of the peristaltic pump rotor during the holding interval; i) using the processor to generate an alert signal if the maximum pressure recorded in step g) is below a first predetermined threshold value and/or the pressure drop measured in step h) is above a second predetermined threshold value; a) providing a pump system comprising: a peristaltic pump rotor; a tube; a valve; a pressure sensor; a comparator; and a processor; wherein: the valve is situated on the tube downstream of the peristaltic pump rotor; and the pressure sensor is arranged to sense the fluid pressure in the tube downstream of the peristaltic pump rotor and upstream of the valve; and the peristaltic pump rotor includes at least one member having a tube contact portion; the at least one member being rotatable about a drive axis to move the tube contact portion along an arcuate path, the tube contact portion being configured to occlude the tube; the valve is situated on the tube downstream of the peristaltic pump rotor; and the pressure sensor is arranged to sense the fluid pressure in the tube downstream of the peristaltic pump rotor and upstream of the valve; and the peristaltic pump rotor includes at least one member having a tube contact portion; the at least one member being rotatable about a drive axis to move the tube contact portion along an arcuate path, the tube contact portion being configured to occlude the tube; b) providing a fluid in the tube; c) arranging the pump system such that the valve is open, the peristaltic pump rotor is inactive and the tube contact portion is occluding the tube; d) closing the valve; e) actuating the peristaltic pump rotor from a first rotor position to a second rotor position such that the peristaltic pump rotor is angularly displaced about the drive axis by a predetermined priming angular displacement; f) holding the peristaltic pump rotor in the second rotor position for a holding interval of predetermined duration; g) using the pressure sensor to measure maximum pressure of the fluid in the tube downstream of the peristaltic pump rotor during and/or after completing step e); h) using the pressure sensor to measure any pressure drop in the fluid in the tube downstream of the peristaltic pump rotor during the holding interval; i) using the processor to generate an alert signal if the maximum pressure recorded in step g) is below a first predetermined threshold value and/or the pressure drop measured in step h) is above a second predetermined threshold value;