How can one test a sewage ejector pump?
Most sewage ejection pumps have two cords.  One is the power for the motor.  The other goes to the float switch.  The power cord is a regular plug.  The float switch cord has a plug on the end with female on one side and male on the other.  The power's plug is inserted into the female side of the float switch plug.  The male side of the float plug is then inserted into an electrical outlet.  When the water level trips the float, the float's plug "opens" to give power to the motor's cord.  If you want to test the pump manually, find the outlet the cords are plugged into, unplug the motor's plug from the float's and insert the motor's plug directly into the outlet, bypassing the float.  When you're satisfied, insert the motor's plug back into the float plug and insert the float plug back into the electrical outlet.