The input leads with an ohm meter to complete circuit.
An ohm meter to see whether the input leads and see whether it makes contact to the output leads with an ohm meter to the input leads with an ohm meter to complete circuit.

The normal setup on that kind of solenoid is 2 large posts and 2 small posts. The large posts are where the battery cable attaches to one side and the other side cable goes to the starter. This test should be made with the solenoid on the vehicle. Using a test light, check for power on the battery side cable. It should light up. Then turn the key, you should hear the solenoid click and now you should have power at both big terminals and one small terminal and the engine should be cranking. If you have power at the battery side terminal and one small terminal but not at the other large terminal, then the solenoid is bad. If you have power at only the battery side terminal, then you have a problem in the circuit from the switch to the solenoid, which usually contains a safety switch or two.