Add automatic refund functionality

Author: kronosapiens

contracts/colony/ColonyFunding.sol

@@ -461,6 +461,8 @@ contract ColonyFunding is ColonyStorage { // ignore-swc-123
   }
 
   function processPayout(uint256 _fundingPotId, address _token, uint256 _payout, address payable _user) private {
+    refundDomain(_fundingPotId, _token);
+
     IColonyNetwork colonyNetworkContract = IColonyNetwork(colonyNetworkAddress);
     address payable metaColonyAddress = colonyNetworkContract.getMetaColony();
 
@@ -491,4 +493,13 @@ contract ColonyFunding is ColonyStorage { // ignore-swc-123
 
     emit PayoutClaimed(msgSender(), _fundingPotId, _token, remainder);
   }
+
+  function refundDomain(uint256 _fundingPotId, address _token) private {
+    FundingPot storage fundingPot = fundingPots[_fundingPotId];
+    if (fundingPot.payouts[_token] < fundingPot.balance[_token]) {
+      uint256 domainId = getDomainFromFundingPot(_fundingPotId);
+      uint256 surplus = sub(fundingPot.balance[_token], fundingPot.payouts[_token]);
+      moveFundsBetweenPotsFunctionality(_fundingPotId, domains[domainId].fundingPotId, surplus, _token);
+    }
+  }
 }

test/contracts-network/colony-expenditure.js

@@ -685,6 +685,35 @@ contract("Colony Expenditure", (accounts) => {
       expect(potPayout).to.be.zero;
     });
 
+    it("should automatically reclaim funds if there is excess funding for a token", async () => {
+      await colony.setExpenditureRecipient(expenditureId, SLOT0, RECIPIENT, { from: ADMIN });
+      await colony.setExpenditurePayout(expenditureId, SLOT0, token.address, WAD, { from: ADMIN });
+
+      const expenditure = await colony.getExpenditure(expenditureId);
+      await colony.moveFundsBetweenPots(
+        1,
+        UINT256_MAX,
+        1,
+        UINT256_MAX,
+        UINT256_MAX,
+        domain1.fundingPotId,
+        expenditure.fundingPotId,
+        WAD.muln(2),
+        token.address
+      );
+      await colony.finalizeExpenditure(expenditureId, { from: ADMIN });
+
+      const balanceBefore = await colony.getFundingPotBalance(domain1.fundingPotId, token.address);
+      await colony.claimExpenditurePayout(expenditureId, SLOT0, token.address);
+      const balanceAfter = await colony.getFundingPotBalance(domain1.fundingPotId, token.address);
+      expect(balanceAfter.sub(balanceBefore)).to.eq.BN(WAD);
+
+      const potBalance = await colony.getFundingPotBalance(expenditure.fundingPotId, token.address);
+      const potPayout = await colony.getFundingPotPayout(expenditure.fundingPotId, token.address);
+      expect(potBalance).to.be.zero;
+      expect(potPayout).to.be.zero;
+    });
+
     it("if skill is set, should emit two reputation updates", async () => {
       await colony.setExpenditureRecipient(expenditureId, SLOT0, RECIPIENT, { from: ADMIN });
       await colony.setExpenditurePayout(expenditureId, SLOT0, token.address, WAD, { from: ADMIN });