Cover the script systematically
Test independent vowels, consonants, dependent vowel signs, virama, anusvara, visarga, digits, punctuation, and mixed-language text. Include both common and difficult conjuncts.
Compare shaped output
Shape the same corpus with the reference and exported fonts. Glyph IDs, clusters, advances, and offsets should remain identical when only outlines changed.
Validate the binary
Confirm table offsets, lengths, checksums, loca entries, contour closure, coordinate limits, and every GSUB or GPOS glyph reference before allowing download.