Mutation testing comes to DAML

Summary: Trail of Bits added DAML support to Mewt, its open-source mutation-testing engine, generating mutants including two built for DAML's authorization primitives - controller party swap and controller party removal - and running them through an existing test suite to count survivors. In a worked example of a conditional payment requiring both buyer and seller to sign off, Mewt generated seven mutants, the suite caught three, and four survived while coverage still reported 100%.
What you should know: A surviving mutant let the seller release the buyer's money to themselves without the buyer's confirmation, and no test failed - so a contract that type-checks and shows full coverage can still ship with one required approval instead of two.

Read the original at Trail of Bits Blog ↗