+1 on the snap test.
A 'focus snap' test is surprisingly telling. Really good optics come to a distinct focus, often described as snapping to focus.
It works very well in daytime, possibly even easier to interpret than at night.
Every optic I've had that snapped to focus tested extremely well by other methods.
I also, assuming a daytime viewing, use bolt threads on signs and telephone poles as a nice evenly spaced linear test target. Tiny print is also excellent, if either falls within view.
Bare wire runs and straight edges of shiny objects show CA pretty easily
For more formal testing, an artificial star (Hubble Optics or a chromed ball bearing in the sun or laser lit) and Suiter intra/extra focal comparision, and/or a Ronchi tester.
One warning, if too close (and SCTs are particularly sensitive to enough distance), artificial star can give false indications on SA, IIRC. The other aberrations will show up, at least with a Ronchi.
The Suiter is hard for most to interpret, but a near match in and out of focus means a good figure.
A Ronchi tester is much more straightforward to interpret and easily identify many issues. They are a bit hard to find at the moment, but you can download files than can print on printer acetate.
But I like the snap test as a first step