Update hardhat version and fix unit tests

package.json

@@ -45,7 +45,7 @@
     "eslint-config-keep": "github:keep-network/eslint-config-keep#0c27ade",
     "ethereum-waffle": "^3.3.0",
     "ethers": "^5.0.32",
-    "hardhat": "^2.1.1",
+    "hardhat": "^2.6.1",
     "hardhat-deploy": "^0.8.11",
     "hardhat-gas-reporter": "^1.0.4",
     "prettier": "^2.3.2",

test/Auction.test.js

@@ -7,6 +7,7 @@ const {
   pastEvents,
   increaseTime,
   impersonateAccount,
+  isCodeAt,
 } = require("./helpers/contract-test-helpers")
 
 const { BigNumber } = ethers
@@ -150,6 +151,9 @@ describe("Auction", () => {
         // add 100sec
         await increaseTime(100)
 
+        // make sure auction did not self destruct
+        expect(await isCodeAt(auction.address)).to.be.true
+
         expect(await auction.isOpen()).to.be.equal(true)
       })
     })
@@ -164,6 +168,7 @@ describe("Auction", () => {
       })
 
       it("should be opened", async () => {
+        expect(await isCodeAt(auction.address)).to.be.true
         expect(await auction.isOpen()).to.be.equal(true)
       })
 
@@ -275,17 +280,15 @@ describe("Auction", () => {
     })
 
     context("when the auction was fully paid off and is closed", () => {
-      it("should revert on taking offer again", async () => {
+      it("should destroy the auction", async () => {
         // Increase time 1h -> 3600sec
         await increaseTime(3600)
 
         // take the entire auction
         await auction.connect(bidder1).takeOffer(auctionAmountDesired)
 
-        // another bidder is trying to take offer on a closed auction
-        await expect(
-          auction.connect(bidder2).takeOffer(BigNumber.from(1))
-        ).to.be.revertedWith("Address: call to non-contract")
+        // the auction contract address should not store code anymore
+        expect(await isCodeAt(auction.address)).to.be.false
       })
     })
 
@@ -516,14 +519,18 @@ describe("Auction", () => {
           // Increase time so the auction ends
           // 3,600 + 82,800 + 1 = 86401sec (auction ended)
           await increaseTime(82801)
+          // when auction ends and is partially filled, it should not self
+          // destruct
+          expect(await isCodeAt(auction.address)).to.be.true
+
           // when auction ends and is partially filled, it should stay opened
           expect(await auction.isOpen()).to.be.equal(true)
         })
       }
     )
 
     context("when the auction was fully paid off in partial offers", () => {
-      it("should revert on taking another offer", async () => {
+      it("should destroy the auction", async () => {
         // Auction amount desired: 1 * 10^18
         // Increase time 1h -> 3600sec
         await increaseTime(3600)
@@ -538,9 +545,7 @@ describe("Auction", () => {
           .amountOutstanding()
         await auction.connect(bidder2).takeOffer(amountOutstanding)
 
-        await expect(
-          auction.connect(bidder2).takeOffer(BigNumber.from(1))
-        ).to.be.revertedWith("Address: call to non-contract")
+        expect(await isCodeAt(auction.address)).to.be.false
       })
     })
   })
@@ -558,21 +563,21 @@ describe("Auction", () => {
     })
 
     context("when the auction is open and there are no fills", () => {
-      it("should early close the auction", async () => {
+      it("should destroy the auction", async () => {
         await auction.connect(auctioneerSigner).earlyClose()
 
-        expect(await auction.isOpen()).to.be.false
+        expect(await isCodeAt(auction.address)).to.be.false
       })
     })
 
     context("when the auction is open and there are partial fills", () => {
-      it("should early close the auction", async () => {
+      it("should destroy the auction", async () => {
         const partialOfferAmount = auctionAmountDesired.div(BigNumber.from("2"))
         await auction.connect(bidder1).takeOffer(partialOfferAmount)
 
         await auction.connect(auctioneerSigner).earlyClose()
 
-        expect(await auction.isOpen()).to.be.false
+        expect(await isCodeAt(auction.address)).to.be.false
       })
     })
 
@@ -583,19 +588,6 @@ describe("Auction", () => {
         )
       })
     })
-
-    context("when the auction is closed", () => {
-      it("should revert", async () => {
-        // close the auction by taking the whole amount
-        await auction.connect(bidder1).takeOffer(auctionAmountDesired)
-
-        // Will be reverted due to onlyAuctioneer modifier violation as
-        // Auction storage has been destroyed by harikari and current
-        // auctioneer is a zero address.
-        await expect(auction.connect(auctioneerSigner).earlyClose()).to.be
-          .reverted
-      })
-    })
   })
 
   describe("amountTransferred", () => {

test/Auctioneer.test.js

@@ -5,6 +5,7 @@ const {
   to1e18,
   pastEvents,
   increaseTime,
+  isCodeAt,
 } = require("./helpers/contract-test-helpers")
 
 const auctionLength = 86400 // 24h in sec
@@ -264,10 +265,10 @@ describe("Auctioneer", () => {
     })
 
     context("when the auction is still open", () => {
-      it("should close the auction", async () => {
+      it("should destroy the auction", async () => {
         await auctioneer.connect(bidder).publicEarlyCloseAuction(auctionAddress)
 
-        expect(await auction.isOpen()).to.be.false
+        expect(await isCodeAt(auctionAddress)).to.be.false
       })
 
       it("should emit the auction closed event", async () => {

test/helpers/contract-test-helpers.js

@@ -78,12 +78,20 @@ async function resetFork(blockNumber) {
   })
 }
 
+// This function checks whether the given address stores contract code. It
+// can be used to determine whether a contract stored at the given address has
+// self destructed.
+async function isCodeAt(address) {
+  return (await ethers.provider.getCode(address)) != ethers.utils.hexlify("0x")
+}
+
 module.exports.to1ePrecision = to1ePrecision
 module.exports.to1e18 = to1e18
 module.exports.pastEvents = pastEvents
 module.exports.lastBlockTime = lastBlockTime
 module.exports.increaseTime = increaseTime
 module.exports.impersonateAccount = impersonateAccount
 module.exports.resetFork = resetFork
+module.exports.isCodeAt = isCodeAt
 
 module.exports.ZERO_ADDRESS = "0x0000000000000000000000000000000000000000"

test/system/liquidation-multiple-take-offers.test.js

@@ -7,6 +7,7 @@ const {
   resetFork,
   ZERO_ADDRESS,
   increaseTime,
+  isCodeAt,
 } = require("../helpers/contract-test-helpers")
 const {
   underwriterAddress,
@@ -128,8 +129,8 @@ describeFn("System -- multiple partial fills", () => {
       tx = await auction.connect(bidder2).takeOffer(lotSize.mul(60).div(100))
     })
 
-    it("should close auction", async () => {
-      expect(await auction.isOpen()).to.be.false
+    it("should destroy auction", async () => {
+      expect(await isCodeAt(auction.address)).to.be.false
     })
 
     it("should decrease the amount of TBTC for bidders", async () => {
@@ -177,7 +178,7 @@ describeFn("System -- multiple partial fills", () => {
       expect(parseInt(tx.gasLimit)).to.be.lessThan(370000)
 
       const txReceipt = await ethers.provider.getTransactionReceipt(tx.hash)
-      expect(parseInt(txReceipt.gasUsed)).to.be.lessThan(181000)
+      expect(parseInt(txReceipt.gasUsed)).to.be.lessThan(280000)
     })
   })
 })

test/system/liquidation.test.js

@@ -6,6 +6,7 @@ const {
   resetFork,
   ZERO_ADDRESS,
   increaseTime,
+  isCodeAt,
 } = require("../helpers/contract-test-helpers")
 const hre = require("hardhat")
 
@@ -135,8 +136,8 @@ describeFn("System -- liquidation", () => {
       tx = await auction.takeOffer(lotSize)
     })
 
-    it("should close auction", async () => {
-      expect(await auction.isOpen()).to.be.false
+    it("should destroy auction", async () => {
+      expect(await isCodeAt(auction.address)).to.be.false
     })
 
     it("should spend bidder's TBTC", async () => {
@@ -180,7 +181,7 @@ describeFn("System -- liquidation", () => {
       await expect(parseInt(tx.gasLimit)).to.be.lessThan(518000)
 
       const txReceipt = await ethers.provider.getTransactionReceipt(tx.hash)
-      await expect(parseInt(txReceipt.gasUsed)).to.be.lessThan(255000)
+      await expect(parseInt(txReceipt.gasUsed)).to.be.lessThan(392000)
     })
   })
 })

test/system/surplus-for-auction.test.js

@@ -6,6 +6,7 @@ const {
   resetFork,
   to1ePrecision,
   ZERO_ADDRESS,
+  isCodeAt,
 } = require("../helpers/contract-test-helpers")
 const Auction = hre.artifacts.readArtifactSync("Auction")
 const { initContracts } = require("./init-contracts")
@@ -159,7 +160,7 @@ describeFn("System -- buying a deposit with surplus", () => {
     })
 
     it("should early close cov pool auction for deposit2", async () => {
-      expect(await auction.isOpen()).to.be.false
+      expect(await isCodeAt(auction.address)).to.be.false
     })
 
     it("should buy deposit3 with surplus TBTC without opening an auction", async () => {