Because OpenType features often work with characters not in unicode it is tedious to create proofing documents that test OpenType features. This can be very time consuming when working with complex non-Latin scripts like Arabic and Devanagari. It would be helpful if Glyphs could generate a list of text strings that can be copy/pasted into another application for rapidly proofing a font with complex OpenType features.
Can you give an example?
There is a script by Toshi that puts all alternates into ss20. Perhaps that helps you achieve the same goal.
Devanagari half forms and conjuncts are an example. There are hundreds of them and it isn’t practical to just generate test strings for every possible conjunct, print that, and then only review the glyphs that have been designed. Likewise, a font with lots of decorative ligatures isn’t designed in totality and tested all at once. It would be very convenient to quickly test the ligatures that are in the font. I don’t think that putting these glyphs into a stylistic set works because they’re not alternates for any one form and are accessed via a sequence of glyphs.