Merge pull request #2060 from kleros/fix/draw-empty-address-bug

fix(DK): no empty addresses after draw

Author: jaybuidl

contracts/src/arbitration/dispute-kits/DisputeKitClassicBase.sol

@@ -229,6 +229,10 @@ abstract contract DisputeKitClassicBase is IDisputeKit, Initializable, UUPSProxi
  bytes32 key = bytes32(uint256(courtID)); // Get the ID of the tree.
 
  drawnAddress = sortitionModule.draw(key, _coreDisputeID, _nonce);
+ if (drawnAddress == address(0)) {
+ // Sortition can return 0 address if no one has staked yet.
+ return drawnAddress;
+ }
 
  if (_postDrawCheck(round, _coreDisputeID, drawnAddress)) {
  round.votes.push(Vote({account: drawnAddress, commit: bytes32(0), choice: 0, voted: false}));

contracts/test/foundry/KlerosCore.t.sol

@@ -1447,6 +1447,26 @@ contract KlerosCoreTest is Test {
  }
  }
 
+ function test_draw_noEmptyAddresses() public {
+ uint256 disputeID = 0;
+ uint256 roundID = 0;
+
+ vm.prank(disputer);
+ arbitrable.createDispute{value: feeForJuror * DEFAULT_NB_OF_JURORS}("Action");
+ vm.warp(block.timestamp + minStakingTime);
+ sortitionModule.passPhase(); // Generating
+ vm.roll(block.number + rngLookahead + 1);
+ sortitionModule.passPhase(); // Drawing phase
+
+ core.draw(disputeID, DEFAULT_NB_OF_JURORS); // No one is staked so check that the empty addresses are not drawn.
+
+ KlerosCoreBase.Round memory round = core.getRoundInfo(disputeID, roundID);
+ assertEq(round.drawIterations, 3, "Wrong drawIterations number");
+
+ (, , , , uint256 nbVoters, ) = disputeKit.getRoundInfo(disputeID, roundID, 0);
+ assertEq(nbVoters, 0, "nbVoters should be 0");
+ }
+
  function test_draw_parentCourts() public {
  uint96 newCourtID = 2;
  uint256 disputeID = 0;