Tout de bon !
Romand French
Said in the canton of Vaud
All the best
Tout de bon! is what you say on taking leave. According to the Base de données lexicographiques panfrancophone (BDLP), which takes over for Switzerland the work of André Thibault’s Dictionnaire suisse romand, it is a familiar formula of good wishes, in use in French-speaking Switzerland; in the Jura people also say tout du bon. The database records it on French-Swiss radio in 1976, from a Lausanne informant in 1977, to end a phone call, and from a man of about seventy from Delémont in 1993. You can also wish it to someone, for a diploma passed or for the new year.
In standard French, tout de bon exists too, but there it only means “really, seriously”, and has done so since Molière and Rousseau, according to the BDLP.
Where does the French-Swiss use come from? The BDLP apparently judges it peculiar to French-speaking Switzerland and suggests, with a “perhaps”, comparing it with German alles Gute, the wish you make for a birthday, for example. The Wiktionnaire is more assertive and sees a Germanism in it. Between the two, the German trail remains a hypothesis.
You say it on leaving, or before a test:
Sources: Base de données lexicographiques panfrancophone, Swiss database, “tout de/du bon !” and “tout de bon (souhaiter ~)”; Wiktionnaire, “tout de bon”.