Deposit refunds

[guidanoli]

📚 Specification

Draft on HackMD

📈 Subtasks

Based on the specification, we list all contracts-related tasks below.
The tasks are ordered in such a way that is easier to implement them.

• Add IRefundOutputBuilder
• Add RefundOutputBuilder
• Add RefundOutputBuilder to deployment script (and Cannonfile)
• Add wasInputFinalized function to IOutputsMerkleRootValidator
• Implement wasInputFinalized function in AbstractConsensus
• Add IRefundOutputBuilder field to WithdrawalConfig struct
• Move NotForeclosed from IApplicationWithdrawal to IApplicationForeclosure
• Add getRefundOutputBuilder function to IApplicationRefund interface
• Add validateInput function to IApplicationRefund interface
• Add issueRefund function to IApplicationRefund interface
• Add wasRefundIssued function to IApplicationRefund interface
• Add getNumberOfIssuedRefunds function to IApplicationRefund interface

⛓️‍💥 Breaking changes

No breaking changes would be added with this feature.

🧪 Tests

Based on the expected behavior of the new entrypoints and parameters,
here are some test cases that should validate their correct implementation.

• Deploy app with address zero as refund output builder
• Deploy app with fuzzed refund output builder and test getters and event
• Ensure initial issued-refund count is zero
• Ensure no refunds were issued initially
• Attempt to validate invalid input index
• Attempt to validate invalid input
• Add fuzzed input and validate it on the app contract
• Attempt to issue refund when app is not foreclosed
• Attempt to issue refund for invalid input index
• Attempt to issue refund for invalid input
• Attempt to issue refund for finalized input
• Attempt to issue refund for non-deposit input
• Attempt to issue refund for same input twice
• Issue refund with fuzzed Ether deposit and test events/getters
• Issue refund with fuzzed ERC-20 deposit and test events/getters
• Issue refund with fuzzed ERC-721 deposit and test events/getters
• Issue refund with fuzzed single ERC-1155 deposit and test events/getters
• Issue refund with fuzzed batch ERC-1155 deposit and test events/getters