refactor: immutable euint64 and skipped test

contracts/governance/ConfidentialERC20Votes.sol

@@ -80,9 +80,7 @@ abstract contract ConfidentialERC20Votes is IConfidentialERC20Votes, Confidentia
 
     /// @notice Constant for zero using TFHE.
     /// @dev    Since it is expensive to compute 0, it is stored instead.
-    ///         However, is not possible to define it as constant due to TFHE constraints.
-    /* solhint-disable var-name-mixedcase*/
-    euint64 private _EUINT64_ZERO;
+    euint64 private immutable _EUINT64_ZERO;
 
     /**
      * @param owner_        Owner address.
@@ -168,11 +166,7 @@ abstract contract ConfidentialERC20Votes is IConfidentialERC20Votes, Confidentia
             revert GovernorInvalid();
         }
 
-        if (blockNumber >= block.number) {
-            revert BlockNumberEqualOrHigherThanCurrentBlock();
-        }
-
-        votes = _getPriorVote(account, blockNumber);
+        votes = getPriorVotes(account, blockNumber);
         TFHE.allow(votes, msg.sender);
     }
 
@@ -223,26 +217,24 @@ abstract contract ConfidentialERC20Votes is IConfidentialERC20Votes, Confidentia
         _moveDelegates(currentDelegate, delegatee, delegatorBalance);
     }
 
-    function _getPriorVote(address account, uint256 blockNumber) internal view returns (euint64 votes) {
+    function _getPriorVote(address account, uint256 blockNumber) internal view virtual returns (euint64 votes) {
         uint32 nCheckpoints = numCheckpoints[account];
 
         if (nCheckpoints == 0) {
-            /// If there is no checkpoint for the `account`, return encrypted zero.
-            /// @dev It will not be possible to reencrypt it by the `account`.
-            votes = _EUINT64_ZERO;
+            /// @dev If there is no checkpoint for the `account`, return empty handle.
+            return votes;
         } else if (_checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
-            /// First, check the most recent balance.
-            votes = _checkpoints[account][nCheckpoints - 1].votes;
+            /// @dev First, check the most recent balance.
+            return _checkpoints[account][nCheckpoints - 1].votes;
         } else if (_checkpoints[account][0].fromBlock > blockNumber) {
-            /// Then, check if there is zero balance.
-            /// @dev It will not be possible to reencrypt it by the `account`.
-            votes = _EUINT64_ZERO;
+            /// @dev Then, check if there is zero balance. If so, return empty handle.
+            return votes;
         } else {
-            /// Else, search for the voting power at the `blockNumber`.
+            /// @dev Else, search for the voting power at the `blockNumber`.
             uint32 lower = 0;
             uint32 upper = nCheckpoints - 1;
             while (upper > lower) {
-                /// Ceil to avoid overflow.
+                /// @dev Ceil to avoid overflow.
                 uint32 center = upper - (upper - lower) / 2;
                 Checkpoint memory cp = _checkpoints[account][center];
 
@@ -254,7 +246,7 @@ abstract contract ConfidentialERC20Votes is IConfidentialERC20Votes, Confidentia
                     upper = center - 1;
                 }
             }
-            votes = _checkpoints[account][lower].votes;
+            return _checkpoints[account][lower].votes;
         }
     }
 

contracts/governance/ConfidentialGovernorAlpha.sol

@@ -227,16 +227,12 @@ abstract contract ConfidentialGovernorAlpha is Ownable2Step, GatewayCaller {
     ICompoundTimelock public immutable TIMELOCK;
 
     /// @notice Constant for zero using TFHE.
-    /// @dev    Since it is expensive to compute 0, it is stored instead.
-    ///         However, is not possible to define it as constant due to TFHE constraints.
-    /* solhint-disable var-name-mixedcase*/
-    euint64 private _EUINT64_ZERO;
+    /// @dev    Since it is expensive to compute 0, it is stored once instead.
+    euint64 private immutable _EUINT64_ZERO;
 
     /// @notice Constant for PROPOSAL_THRESHOLD using TFHE.
-    /// @dev    Since it is expensive to compute 0, it is stored instead.
-    ///         However, is not possible to define it as constant due to TFHE constraints.
-    /* solhint-disable var-name-mixedcase*/
-    euint64 private _EUINT64_PROPOSAL_THRESHOLD;
+    /// @dev    Since it is expensive to compute the PROPOSAL_THRESHOLD, it is stored once instead.
+    euint64 private immutable _EUINT64_PROPOSAL_THRESHOLD;
 
     /// @notice The total number of proposals made.
     ///         It includes all proposals, including the ones that
@@ -465,10 +461,8 @@ abstract contract ConfidentialGovernorAlpha is Ownable2Step, GatewayCaller {
             description
         );
 
-        ebool canPropose = TFHE.lt(
-            _EUINT64_PROPOSAL_THRESHOLD,
-            CONFIDENTIAL_ERC20_VOTES.getPriorVotesForGovernor(msg.sender, block.number - 1)
-        );
+        euint64 priorVotes = CONFIDENTIAL_ERC20_VOTES.getPriorVotesForGovernor(msg.sender, block.number - 1);
+        ebool canPropose = TFHE.lt(_EUINT64_PROPOSAL_THRESHOLD, priorVotes);
 
         uint256[] memory cts = new uint256[](1);
         cts[0] = Gateway.toUint256(canPropose);

hardhat.config.ts

@@ -99,6 +99,7 @@ const config: HardhatUserConfig = {
   },
   networks: {
     hardhat: {
+      gas: "auto",
       accounts: {
         count: 10,
         mnemonic,

package.json

@@ -95,7 +95,7 @@
   },
   "dependencies": {
     "fhevm": "^0.6.1",
-    "@openzeppelin/contracts": "^5.0.2",
-    "@openzeppelin/contracts-upgradeable": "^5.0.2"
+    "@openzeppelin/contracts": "^5.1.0",
+    "@openzeppelin/contracts-upgradeable": "^5.1.0"
   }
 }

test/governance/ConfidentialERC20Votes.test.ts

@@ -389,12 +389,12 @@ describe("ConfidentialERC20Votes", function () {
       .connect(this.signers.bob)
       .getPriorVotes(this.signers.bob.address, latestBlockNumber);
 
-    // It is an encrypted constant that is not reencryptable by Bob.
-    expect(currentVoteHandle).not.to.be.eq(0n);
+    // The handle is not set.
+    expect(currentVoteHandle).to.be.eq(0n);
 
     await expect(
       reencryptEuint64(this.signers.bob, this.instance, currentVoteHandle, this.confidentialERC20Votes),
-    ).to.be.rejectedWith("Invalid contract address.");
+    ).to.be.rejectedWith("Handle is not initialized");
 
     // 3. If a checkpoint exists using getPriorVotes but block.number < block of first checkpoint
     latestBlockNumber = await ethers.provider.getBlockNumber();
@@ -408,11 +408,11 @@ describe("ConfidentialERC20Votes", function () {
       .getPriorVotes(this.signers.bob.address, latestBlockNumber);
 
     // It is an encrypted constant that is not reencryptable by Bob.
-    expect(currentVoteHandle).not.to.be.eq(0n);
+    expect(currentVoteHandle).to.eq(0n);
 
     await expect(
       reencryptEuint64(this.signers.bob, this.instance, currentVoteHandle, this.confidentialERC20Votes),
-    ).to.be.rejectedWith("Invalid contract address.");
+    ).to.be.rejectedWith("Handle is not initialized");
   });
 
   it("can do multiple checkpoints and access the values when needed", async function () {
@@ -541,18 +541,16 @@ describe("ConfidentialERC20Votes", function () {
     );
   });
 
-  // TODO: fix issue with mining
-  it.skip("number of checkpoints is incremented once per block, even when written multiple times in same block", async function () {
+  it("number of checkpoints is incremented once per block, even when written multiple times in same block", async function () {
     await network.provider.send("evm_setAutomine", [false]);
     await network.provider.send("evm_setIntervalMining", [0]);
 
-    // do two checkpoints in same block
-    const tx1 = this.confidentialERC20Votes.connect(this.signers.alice).delegate(this.signers.bob);
-    const tx2 = this.confidentialERC20Votes.connect(this.signers.alice).delegate(this.signers.carol);
+    // @dev There are two checkpoints in the same block.
+    await this.confidentialERC20Votes.connect(this.signers.alice).delegate(this.signers.bob);
+    await this.confidentialERC20Votes.connect(this.signers.alice).delegate(this.signers.carol);
 
     await network.provider.send("evm_mine");
     await network.provider.send("evm_setAutomine", [true]);
-    await Promise.all([tx1, tx2]);
 
     expect(await this.confidentialERC20Votes.numCheckpoints(this.signers.alice.address)).to.be.equal(0n);
     expect(await this.confidentialERC20Votes.numCheckpoints(this.signers.bob.address)).to.be.equal(1n);

test/governance/ConfidentialGovernorAlpha.test.ts

@@ -1123,6 +1123,8 @@ describe("ConfidentialGovernorAlpha", function () {
       "TransactionTooLateForExecution",
     );
 
+    await mineNBlocks(1);
+
     proposalInfo = await this.governor.getProposalInfo(proposalId);
     // 9 ==> Expired
     expect(proposalInfo.state).to.equal(9);