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

Recommended

• Zeppelin OS The transparent proxy pattern