la qualité se révèle à l’usage signifie anglais

the proof of the pudding is in the eating▼(the only real test of something is as what it is intended to be used for)
phrase
[UK: ðə pruːf əv ðə ˈpʊd.ɪŋ ɪz ɪn ðə ˈiːt.ɪŋ] [US: ðə ˈpruːf əv ðə ˈpʊd.ɪŋ ˈɪz ɪn ðə ˈiːt.ɪŋ]