Add ERC721Votes for NFT-based governance (#2944)

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
Co-authored-by: Hadrien Croubois <hadrien@openzeppelin.com>

contracts/mocks/CheckpointsImpl.sol

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../utils/Checkpoints.sol";
+
+contract CheckpointsImpl {
+    using Checkpoints for Checkpoints.History;
+
+    Checkpoints.History private _totalCheckpoints;
+
+    function latest() public view returns (uint256) {
+        return _totalCheckpoints.latest();
+    }
+
+    function getAtBlock(uint256 blockNumber) public view returns (uint256) {
+        return _totalCheckpoints.getAtBlock(blockNumber);
+    }
+
+    function push(uint256 value) public returns (uint256, uint256) {
+        return _totalCheckpoints.push(value);
+    }
+}

contracts/mocks/ERC721VotesMock.sol

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../token/ERC721/extensions/draft-ERC721Votes.sol";
+
+contract ERC721VotesMock is ERC721Votes {
+    constructor(string memory name, string memory symbol) ERC721(name, symbol) EIP712(name, "1") {}
+
+    function getTotalSupply() public view returns (uint256) {
+        return _getTotalSupply();
+    }
+
+    function mint(address account, uint256 tokenId) public {
+        _mint(account, tokenId);
+    }
+
+    function burn(uint256 tokenId) public {
+        _burn(tokenId);
+    }
+
+    function getChainId() external view returns (uint256) {
+        return block.chainid;
+    }
+}

contracts/mocks/GovernorMock.sol

@@ -15,7 +15,7 @@ contract GovernorMock is
 {
     constructor(
         string memory name_,
-        ERC20Votes token_,
+        IVotes token_,
         uint256 votingDelay_,
         uint256 votingPeriod_,
         uint256 quorumNumerator_

contracts/mocks/GovernorPreventLateQuorumMock.sol

@@ -17,7 +17,7 @@ contract GovernorPreventLateQuorumMock is
 
     constructor(
         string memory name_,
-        ERC20Votes token_,
+        IVotes token_,
         uint256 votingDelay_,
         uint256 votingPeriod_,
         uint256 quorum_,

contracts/mocks/GovernorTimelockCompoundMock.sol

@@ -15,7 +15,7 @@ contract GovernorTimelockCompoundMock is
 {
     constructor(
         string memory name_,
-        ERC20Votes token_,
+        IVotes token_,
         uint256 votingDelay_,
         uint256 votingPeriod_,
         ICompoundTimelock timelock_,

contracts/mocks/GovernorTimelockControlMock.sol

@@ -15,7 +15,7 @@ contract GovernorTimelockControlMock is
 {
     constructor(
         string memory name_,
-        ERC20Votes token_,
+        IVotes token_,
         uint256 votingDelay_,
         uint256 votingPeriod_,
         TimelockController timelock_,

contracts/mocks/GovernorVoteMock.sol

@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../governance/extensions/GovernorCountingSimple.sol";
+import "../governance/extensions/GovernorVotes.sol";
+
+contract GovernorVoteMocks is GovernorVotes, GovernorCountingSimple {
+    constructor(string memory name_, IVotes token_) Governor(name_) GovernorVotes(token_) {}
+
+    function quorum(uint256) public pure override returns (uint256) {
+        return 0;
+    }
+
+    function votingDelay() public pure override returns (uint256) {
+        return 4;
+    }
+
+    function votingPeriod() public pure override returns (uint256) {
+        return 16;
+    }
+
+    function cancel(
+        address[] memory targets,
+        uint256[] memory values,
+        bytes[] memory calldatas,
+        bytes32 salt
+    ) public returns (uint256 proposalId) {
+        return _cancel(targets, values, calldatas, salt);
+    }
+
+    function getVotes(address account, uint256 blockNumber)
+        public
+        view
+        virtual
+        override(IGovernor, GovernorVotes)
+        returns (uint256)
+    {
+        return super.getVotes(account, blockNumber);
+    }
+}

contracts/mocks/VotesMock.sol

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../governance/utils/Votes.sol";
+
+contract VotesMock is Votes {
+    mapping(address => uint256) private _balances;
+    mapping(uint256 => address) private _owners;
+
+    constructor(string memory name) EIP712(name, "1") {}
+
+    function getTotalSupply() public view returns (uint256) {
+        return _getTotalSupply();
+    }
+
+    function delegate(address account, address newDelegation) public {
+        return _delegate(account, newDelegation);
+    }
+
+    function _getVotingUnits(address account) internal virtual override returns (uint256) {
+        return _balances[account];
+    }
+
+    function mint(address account, uint256 voteId) external {
+        _balances[account] += 1;
+        _owners[voteId] = account;
+        _transferVotingUnits(address(0), account, 1);
+    }
+
+    function burn(uint256 voteId) external {
+        address owner = _owners[voteId];
+        _balances[owner] -= 1;
+        _transferVotingUnits(owner, address(0), 1);
+    }
+
+    function getChainId() external view returns (uint256) {
+        return block.chainid;
+    }
+}

contracts/mocks/wizard/MyGovernor1.sol

@@ -14,7 +14,7 @@ contract MyGovernor1 is
     GovernorVotesQuorumFraction,
     GovernorCountingSimple
 {
-    constructor(ERC20Votes _token, TimelockController _timelock)
+    constructor(IVotes _token, TimelockController _timelock)
         Governor("MyGovernor")
         GovernorVotes(_token)
         GovernorVotesQuorumFraction(4)

contracts/mocks/wizard/MyGovernor2.sol

@@ -16,7 +16,7 @@ contract MyGovernor2 is
     GovernorVotesQuorumFraction,
     GovernorCountingSimple
 {
-    constructor(ERC20Votes _token, TimelockController _timelock)
+    constructor(IVotes _token, TimelockController _timelock)
         Governor("MyGovernor")
         GovernorVotes(_token)
         GovernorVotesQuorumFraction(4)

contracts/mocks/wizard/MyGovernor3.sol

@@ -14,7 +14,7 @@ contract MyGovernor is
     GovernorVotes,
     GovernorVotesQuorumFraction
 {
-    constructor(ERC20Votes _token, TimelockController _timelock)
+    constructor(IVotes _token, TimelockController _timelock)
         Governor("MyGovernor")
         GovernorVotes(_token)
         GovernorVotesQuorumFraction(4)