What do you test?
HINTS: Design QA (diacritics, outline errors, alignment zones, mixed glyphs, ...), Charset, (glyph order, ligatures, duplicates, spaces, hyphens, unicodes...) Font Info (masters, stems, inerpolations, style linking, instance naming, italic angle, vertical metrics, ...), Metrics, Kerning, Features. After export: Indesign, Word, style naming, style linking, features working, kerning working, hinting, ...