feat(EMP contracts): Subsequent liquidations reset withdrawal timer

packages/core/contracts/financial-templates/expiring-multiparty/Liquidatable.sol

@@ -295,6 +295,17 @@ contract Liquidatable is PricelessPositionManager {
             })
         );
 
+        // If this liquidation is a subsequent liquidation on the position, and the liquidation size is larger than
+        // minSponsorTokens, then re-set the liveness. This enables a liquidation against a withdraw request to be
+        // "dragged out" if the position is very large.
+        if (
+            positionToLiquidate.withdrawalRequestPassTimestamp > 0 && // this is a subsequent liquidation.
+            positionToLiquidate.withdrawalRequestPassTimestamp <= getCurrentTime() && // liveness has not passed yet.
+            maxTokensToLiquidate.isGreaterThanOrEqual(minSponsorTokens) // above the minimum threshold.
+        ) {
+            positionToLiquidate.withdrawalRequestPassTimestamp = getCurrentTime().add(liquidationLiveness);
+        }
+
         emit LiquidationCreated(
             sponsor,
             msg.sender,

packages/core/test/financial-templates/Liquidatable.js

@@ -525,6 +525,100 @@ contract("Liquidatable", function(accounts) {
         )
       );
     });
+    it("Multiple partial liquidations re-set liveness timer on withdrawal requests", async () => {
+      // Request a withdrawal.
+      const withdrawalAmount = amountOfSynthetic.divn(5);
+      await liquidationContract.requestWithdrawal({ rawValue: withdrawalAmount.toString() }, { from: sponsor });
+
+      const startingTime = await liquidationContract.getCurrentTime();
+      let expectedTimestamp = toBN(startingTime)
+        .add(liquidationLiveness)
+        .toString();
+
+      assert(
+        expectedTimestamp,
+        (await liquidationContract.positions(sponsor)).withdrawalRequestPassTimestamp.toString()
+      );
+
+      // Advance time by half of the liveness duration.
+      await liquidationContract.setCurrentTime(startingTime.add(liquidationLiveness.divn(2)).toString());
+
+      await liquidationContract.createLiquidation(
+        sponsor,
+        { rawValue: "0" },
+        { rawValue: pricePerToken.toString() },
+        { rawValue: amountOfSynthetic.divn(5).toString() },
+        unreachableDeadline,
+        { from: liquidator }
+      );
+
+      // After the liquidation the liveness timer on the withdrawl request should be re-set to the current time +
+      // the liquidation liveness. This opens the position up to having a subsequent liquidation, if need be.
+      const liquidation1Time = await liquidationContract.getCurrentTime();
+      assert(
+        liquidation1Time.add(liquidationLiveness).toString(),
+        (await liquidationContract.positions(sponsor)).withdrawalRequestPassTimestamp.toString()
+      );
+
+      // Create a subsequent liquidation partial and check that it also advances the withdrawal request timer
+      await liquidationContract.setCurrentTime(liquidation1Time.add(liquidationLiveness.divn(2)).toString());
+
+      await liquidationContract.createLiquidation(
+        sponsor,
+        { rawValue: "0" },
+        { rawValue: pricePerToken.toString() },
+        { rawValue: amountOfSynthetic.divn(5).toString() },
+        unreachableDeadline,
+        { from: liquidator }
+      );
+
+      // Again, verify this is offset correctly.
+      const liquidation2Time = await liquidationContract.getCurrentTime();
+      const expectedWithdrawalRequestPassTimestamp = liquidation2Time.add(liquidationLiveness).toString();
+      assert(
+        expectedWithdrawalRequestPassTimestamp,
+        (await liquidationContract.positions(sponsor)).withdrawalRequestPassTimestamp.toString()
+      );
+
+      // Submitting a liquidation less than the minimum sponsor size should not advance the timer. Start by advancing
+      // time by half of the liquidation liveness.
+      await liquidationContract.setCurrentTime(liquidation2Time.add(liquidationLiveness.divn(2)).toString());
+      await liquidationContract.createLiquidation(
+        sponsor,
+        { rawValue: "0" },
+        { rawValue: pricePerToken.toString() },
+        { rawValue: minSponsorTokens.divn(2).toString() }, // half of the min size. Should not increment timer.
+        unreachableDeadline,
+        { from: liquidator }
+      );
+
+      // Check that the timer has not re-set. expectedWithdrawalRequestPassTimestamp was set after the previous
+      // liquidation (before incrementing the time).
+
+      assert(
+        expectedWithdrawalRequestPassTimestamp,
+        (await liquidationContract.positions(sponsor)).withdrawalRequestPassTimestamp.toString()
+      );
+
+      // Advance timer again to place time after liquidation liveness.
+      await liquidationContract.setCurrentTime(liquidation2Time.add(liquidationLiveness).toString());
+
+      // Now, submitting a withdrawal request should NOT reset liveness (sponsor has passed liveness duration).
+      await liquidationContract.createLiquidation(
+        sponsor,
+        { rawValue: "0" },
+        { rawValue: pricePerToken.toString() },
+        { rawValue: amountOfSynthetic.divn(5).toString() },
+        unreachableDeadline,
+        { from: liquidator }
+      );
+
+      // Check that the time has not advanced.
+      assert(
+        expectedWithdrawalRequestPassTimestamp,
+        (await liquidationContract.positions(sponsor)).withdrawalRequestPassTimestamp.toString()
+      );
+    });
   });
 
   describe("Full liquidation has been created", () => {