Cooked Validators

Copyright Tweag I/O 2024

cooked-validators is a Haskell library to conveniently and efficiently write off-chain code for Cardano smart contracts. This offchain code will be specifically geared to testing and auditing the smart contract in question with further builtin capabilities of the library.

In particular, cooked-validators allows the user to:

• interact with smart contracts written in Plutus or any other language that compiles to UPLC, like for example Plutarch or Aiken, by loading contracts from byte strings
• define transactions in a high level, type-retaining data structure
• submit transactions for validation, while automatically taking care of missing inputs and outputs, balancing, minimum-Ada constraints, collaterals and fees
• construct sequences of transactions in an easy-to-understand abstraction of "the blockchain", which can be instantiated to different actual implementations
• run sequences of transactions in a simulated blockchain
• apply "tweaks" to transactions right before submitting them, where "tweaks" are modifications that are aware of the current state of the simulated blockchain
• compose and deploy tweaks with flexible idioms inspired by linear temporal logic, in order to turn one sequence of transactions into many sequences that might be useful test cases, generalized in Graft
• deploy automated attacks over existing sequences of transactions, such as datum hijacking or double satisfaction attacks, in an attempt to uncover vulnerabilities

You are free to copy, modify, and distribute cooked-validators under the terms of the MIT license. We provide cooked-validators as a research prototype under active development, and it comes as is with no guarantees whatsoever. Check the license for details.

How to integrate cooked-validators in a project

To use cooked-validators, you need

• GHC version 9.6.5
• Cabal version 3.10 or later

1. cooked-validators depends on cardano-haskell-packages to get cardano-related packages and on cardano-node-emulator directly. If you have no constraint on the version of this package, copy the file cabal.project to your project and adapt the packages stanza.

2. Add the following stanza to the file cabal.project

   source-repository-package
     type: git
     location: https://github.com/tweag/cooked-validators
     tag: myTag
     subdir:
       .
   

   where myTag is either a commit hash in the repo, or a tag, such as v4.0.0 (see available releases).

Example

1. Make your project depend on cooked-validators and plutus-script-utils

2. Enter a Cabal read-eval-print-loop (with cabal repl) and create and validate a transaction which transfers 10 Ada from wallet 1 to wallet 2:

   > import Cooked
   > import qualified Plutus.Script.Utils.Ada as Script
   > printCooked . runMockChain . validateTxSkel $
         txSkelTemplate
           { txSkelOuts = [paysPK (wallet 2) (Script.adaValueOf 10)],
             txSkelSigners = [wallet 1]
           }
   [...]
   - UTxO state:
     • pubkey wallet 1
       - Lovelace: 89_828_471
       - (×4) Lovelace: 100_000_000
     • pubkey wallet 2
       - Lovelace: 10_000_000
       - (×5) Lovelace: 100_000_000
     • pubkey wallet 3
       - (×5) Lovelace: 100_000_000
     • pubkey wallet 4
       - (×5) Lovelace: 100_000_000
   [...]

Documentation

• The rendered Haddock for the current main branch can be found here.

• The CHEATSHEET contains many code snippets to quickly get an intuition of how to do things. Use it to discover or search for how to use features of cooked-validators. Note that this is not a tutorial nor a ready-to-use recipes book.

• The IMPORTS file describes and helps to understand our dependencies and naming conventions for imports.

• The BALANCING file thorougly describes cooked-validator's automated balancing mechanism and associated options (including options revolving around fees and collaterals).

• We also have a repository of example contracts with offchain code and tests written using cooked-validators. Note that some examples are not maintained and thus written using older versions of cooked-validators.

• Feel free to visit our issue tracker to seek help about known problems, or report new issues!