Most chargers don’t have built in analyzers. I find I hardly ever worry about it with flashlight batteries……….even though I have the equipment to do it.
Another way to get a ball park figure is to take one of your good current regulated flashlights. One that has constant brightness (meaning constant current to the LED) Put it on medium high level (say around 200 lumens) which would be about 350mA. See how long the light runs before it starts to drop down in brightness. Muiltiply the current by the time and you have approximated mAh. 200 lumen level should give you 3500mAh/350mA = 10 hours.
OK. Maybe not quite that easy to do. You kind of need some equipment. If you could measure the battery current for a given output with your digital multimeter, you’d get a little closer to your ball park figure.