How to test a capacitor?
This circuit from Max Robinson shown below has worked well for me only instead of the transformer I used the primary of an old switch mode charger that provides a stable 340vdc and isolation but there is no reason the circuit below will not work just as well. Also I used my cheap dvm he suggests a parallel 10M but I am not sure why.

The leakage voltage is ILMeasured = V / R.

In my case the leakage was 30V after 10 minutes for a 560u capacitor with 220k series resistor.