You can do a makeshift load test with a voltmeter. Preferably with alligator clips but a manservant will do.
Watch the voltage as you crank the engine. If it drops below 10 volts or thereabouts, the battery is about to bite the dust.
I had already dismissed a bad battery through checking as mentioned. I freed my hoist up today so mower could be lifted for inspection of the drive belts, etc. I wasn't expecting to find anything. You guys are not going to believe what was found. The belt for the mower had jumped the pully and was up around the pto clutch, most of the way. It is binding the turning of engine crank shaft. I've been at it for about two hours and it has not freed up yet. Didn't want to remove the pto, and I don't know why so that will be my next move, then a new belt. Guess I just like checking the hard stuff first.