feat: Populate epoch 0 from initial validator set (#8286)

l1-contracts/src/core/Rollup.sol

@@ -104,6 +104,7 @@ contract Rollup is Leonidas, IRollup, ITestRollup {
     for (uint256 i = 0; i < _validators.length; i++) {
       _addValidator(_validators[i]);
     }
+    setupEpoch();
   }
 
   /**

l1-contracts/src/core/sequencer_selection/Leonidas.sol

@@ -78,11 +78,6 @@ contract Leonidas is Ownable, ILeonidas {
 
   constructor(address _ares) Ownable(_ares) {
     GENESIS_TIME = block.timestamp;
-
-    // We will setup the initial epoch value
-    uint256 seed = _computeNextSeed(0);
-    epochs[0] = Epoch({committee: new address[](0), sampleSeed: type(uint256).max, nextSeed: seed});
-    lastSeed = seed;
   }
 
   /**
@@ -135,10 +130,6 @@ contract Leonidas is Ownable, ILeonidas {
 
   function getCommitteeAt(uint256 _ts) internal view returns (address[] memory) {
     uint256 epochNumber = getEpochAt(_ts);
-    if (epochNumber == 0) {
-      return new address[](0);
-    }
-
     Epoch storage epoch = epochs[epochNumber];
 
     if (epoch.sampleSeed != 0) {
@@ -156,7 +147,7 @@ contract Leonidas is Ownable, ILeonidas {
 
     // Emulate a sampling of the validators
     uint256 sampleSeed = _getSampleSeed(epochNumber);
-    return _sampleValidators(epochNumber, sampleSeed);
+    return _sampleValidators(sampleSeed);
   }
 
   /**
@@ -224,12 +215,11 @@ contract Leonidas is Ownable, ILeonidas {
     uint256 epochNumber = getCurrentEpoch();
     Epoch storage epoch = epochs[epochNumber];
 
-    // For epoch 0 the sampleSeed == type(uint256).max, so we will never enter this
     if (epoch.sampleSeed == 0) {
       epoch.sampleSeed = _getSampleSeed(epochNumber);
       epoch.nextSeed = lastSeed = _computeNextSeed(epochNumber);
 
-      epoch.committee = _sampleValidators(epochNumber, epoch.sampleSeed);
+      epoch.committee = _sampleValidators(epoch.sampleSeed);
     }
   }
 
@@ -326,7 +316,7 @@ contract Leonidas is Ownable, ILeonidas {
 
     // Emulate a sampling of the validators
     uint256 sampleSeed = _getSampleSeed(epochNumber);
-    address[] memory committee = _sampleValidators(epochNumber, sampleSeed);
+    address[] memory committee = _sampleValidators(sampleSeed);
     return committee[_computeProposerIndex(epochNumber, slot, sampleSeed, committee.length)];
   }
 
@@ -415,23 +405,9 @@ contract Leonidas is Ownable, ILeonidas {
    * @dev     Only used internally, should never be called for anything but the "next" epoch
    *          Allowing us to always use `lastSeed`.
    *
-   * @dev     The first epoch will always return an empty list
-   *          If the validator set is empty, we return an empty list
-   *          If the validator set is smaller than the target committee size, we return the full set
-   *          If the validator set is larger than the target committee size, we sample the validators
-   *          by using the seed of the previous epoch to compute an offset for the validator set and then
-   *          we take the next `TARGET_COMMITTEE_SIZE` validators from that offset (wrapping around).
-   *
-   * @param _epoch - The epoch to sample the validators for
-   *
    * @return The validators for the given epoch
    */
-  function _sampleValidators(uint256 _epoch, uint256 _seed) private view returns (address[] memory) {
-    // If we are in the first epoch, we just return an empty list
-    if (_epoch == 0) {
-      return new address[](0);
-    }
-
+  function _sampleValidators(uint256 _seed) private view returns (address[] memory) {
     uint256 validatorSetSize = validatorSet.length();
     if (validatorSetSize == 0) {
       return new address[](0);
@@ -467,6 +443,9 @@ contract Leonidas is Ownable, ILeonidas {
    * @return The sample seed for the epoch
    */
   function _getSampleSeed(uint256 _epoch) private view returns (uint256) {
+    if (_epoch == 0) {
+      return type(uint256).max;
+    }
     uint256 sampleSeed = epochs[_epoch].sampleSeed;
     if (sampleSeed != 0) {
       return sampleSeed;

l1-contracts/test/sparta/Sparta.t.sol

@@ -59,6 +59,14 @@ contract SpartaTest is DecoderBase {
       vm.warp(initialTime);
     }
 
+    address[] memory initialValidators = new address[](_validatorCount);
+    for (uint256 i = 1; i < _validatorCount + 1; i++) {
+      uint256 privateKey = uint256(keccak256(abi.encode("validator", i)));
+      address validator = vm.addr(privateKey);
+      privateKeys[validator] = privateKey;
+      initialValidators[i - 1] = validator;
+    }
+
     registry = new Registry(address(this));
     availabilityOracle = new AvailabilityOracle();
     portalERC20 = new PortalERC20();
@@ -68,7 +76,7 @@ contract SpartaTest is DecoderBase {
       IFeeJuicePortal(address(0)),
       bytes32(0),
       address(this),
-      new address[](0)
+      initialValidators
     );
     inbox = Inbox(address(rollup.INBOX()));
     outbox = Outbox(address(rollup.OUTBOX()));
@@ -78,15 +86,30 @@ contract SpartaTest is DecoderBase {
     merkleTestUtil = new MerkleTestUtil();
     txsHelper = new TxsDecoderHelper();
 
-    for (uint256 i = 1; i < _validatorCount + 1; i++) {
-      uint256 privateKey = uint256(keccak256(abi.encode("validator", i)));
-      address validator = vm.addr(privateKey);
-      privateKeys[validator] = privateKey;
-      rollup.addValidator(validator);
-    }
     _;
   }
 
+  mapping(address => bool) internal _seenValidators;
+  mapping(address => bool) internal _seenCommittee;
+
+  function testInitialCommitteMatch() public setup(4) {
+    address[] memory validators = rollup.getValidators();
+    address[] memory committee = rollup.getCurrentEpochCommittee();
+    assertEq(rollup.getCurrentEpoch(), 0);
+    assertEq(validators.length, 4, "Invalid validator set size");
+    assertEq(committee.length, 4, "invalid committee set size");
+
+    for (uint256 i = 0; i < validators.length; i++) {
+      _seenValidators[validators[i]] = true;
+    }
+
+    for (uint256 i = 0; i < committee.length; i++) {
+      assertTrue(_seenValidators[committee[i]]);
+      assertFalse(_seenCommittee[committee[i]]);
+      _seenCommittee[committee[i]] = true;
+    }
+  }
+
   function testProposerForNonSetupEpoch(uint8 _epochsToJump) public setup(4) {
     if (Constants.IS_DEV_NET == 1) {
       return;