Canton Daml Testing

Overview

Daml Script is the main tool for testing Daml contracts: you submit commands and queries as multiple parties against a fresh, initially-empty, in-process ledger. It's fast and deterministic — ideal for unit-testing authorization rules, choice behavior, and multi-party workflows.

Writing a script

test_transfer : Script ()
test_transfer = do
  alice <- allocateParty "Alice"
  bob   <- allocateParty "Bob"

  -- create + exercise as a party (note the *Cmd variants on the client side)
  cid    <- submit alice (createCmd Token with owner = alice)
  newCid <- submit alice (exerciseCmd cid Transfer with newOwner = bob)

  -- assert an unauthorized action fails
  submitMustFail bob (exerciseCmd newCid Transfer with newOwner = alice)