Who designed the casket test in The Merchant of Venice?
In the play, Portia's father designs the casket test in his will as a way to exert influence on the choice of Portia's suitor even after his death. It is designed so that Portia will marry the suitor who values her for herself.
Shakespeare took the story of the the three caskets from a well-known folk tale. Other writers who had used it before him were John Gower in Confessio amantis, Boccaccio in The Decameron, and the anonymous author of Gesta Romanorum.
Shakespeare combined at least two folk-tale motifs with details from several other sources to create his play.