One way to test electrolytic capacitors is to measure their capacitance. It does not tell the whole story of capacitor condition. Another usually more useful way to measure electrolytic capacitor condition is to use an ESR meter.
EEVblog #365 – ESR Meter Bad Cap Monitor Repair video gives you tips how to use ESR meter to find bad electrolytic capacitors:
An Equivalent Series Resistance Meter article has a good plan for DIY ESR meter. I have built it and found it well working. Building an ESR meter for Testing Electrolytic Capacitors has a nice table of ESR values you could expect from different capacitors and you can find another table here.
Here are links to some other ESR meter plans and information: