notes.md

General Notes and checklists

1. ZeppelinOS Upgradability checklist

Contracts

• You must add initializers.
• Don't forget to initialize the inherited contracts
• Make sure that all the initial values are set in an initializer function. Otherwise, any upgrable instance will not have these fields sets
• When you create new instance of an arbitray contract inside contract, pass the instance of that contract to initialize function
• You can create new contract instances on the fly using BaseApp in ZeppelinOS
• Rememeber nothing prevent malicious actor from sending transactions
• Make sure to add the new variables at the end
• be careful when you introduce new updates to the contracts
• be careful with the solidity inheretance linearization
  • Avoid base contracts swapping
  • Avoid adding new variables to the base contracts. A workaround for this is to declare unused variables on base contracts that you may want to extend in the future, as a means of "reserving" those slots. Note that this trick does not involve increased gas usage.

Unit testing

• ZOS provides TestHelper() function which in turn returns project structure from ZOS.json
• Set NODE_ENV=test truffle test then invoke TestHelper() in the test suit setup
• To generate new instance of contracts use createProxy function
• Truffle does not know how to resolve situations where contracts has functions that have matching names but different operands or arguments. For unit test call initialize manually by using encodeCall