Testing: MCR contract upgradeability

[mzabaluev]

Description

We need to make sure our MCR contract permits upgrading.

Proposed solution

Create an e2e test case testing an upgrade flow:

1. the current MCR contract is deployed on Anvil.
2. The contract is replaced with an updated contract using the built-in update process.
3. The effects of the updated behavior are verified.

Technical details

It's not really important in what way the updated contract is different. The simplest change would be add a statement logging a magic string that is then observed by the test, along with the confirmation that the contract works.

The "update" to the Solidity contract can in fact be a patch applied against the current code. This may prevent bit rot where the updated contract has outdated behavior.