Fix FeeArithmeticTest (#95)

`minutesPassedSinceLastFeeOp()` tests:

- Do not mine a new block if the time increase is `0`.
- Replace “hours” by “minutes”.

All tests:

- Migrate from `th.fastForwardTime()` to `time.increase()` (better reliability with the hardhat’s ethereum client).

contracts/test/CollSurplusPool.js

@@ -1,3 +1,4 @@
+const { time } = require('@nomicfoundation/hardhat-network-helpers');
 const deploymentHelper = require("../utils/deploymentHelpers.js");
 const testHelpers = require("../utils/testHelpers.js");
 const { fundAccounts } = require("../utils/fundAccounts.js");
@@ -64,10 +65,7 @@ contract("CollSurplusPool", async (accounts) => {
     });
 
     // skip bootstrapping phase
-    await th.fastForwardTime(
-      timeValues.SECONDS_IN_ONE_WEEK * 2,
-      web3.currentProvider
-    );
+    await time.increase(timeValues.SECONDS_IN_ONE_WEEK * 2);
 
     // At ETH:USD = 100, this redemption should leave 1 ether of coll surplus
     await th.redeemCollateralAndGetTxObject(A, contracts, B_netDebt);

contracts/test/FeeArithmeticTest.js

@@ -1,3 +1,4 @@
+const { time } = require('@nomicfoundation/hardhat-network-helpers');
 const Decimal = require("decimal.js");
 const deploymentHelper = require("../utils/deploymentHelpers.js")
 const { BNConverter } = require("../utils/BNConverter.js")
@@ -19,7 +20,7 @@ contract('Fee arithmetic tests', async accounts => {
   const [bountyAddress, lpRewardsAddress, multisig] = accounts.slice(997, 1000)
 
   // see: https://docs.google.com/spreadsheets/d/1RbD8VGzq7xFgeK1GOkz_9bbKVIx-xkOz0VsVelnUFdc/edit#gid=0
-  // Results array, maps seconds to expected hours passed output (rounded down to nearest hour).
+  // Results array, maps seconds to expected minutes passed output (rounded down to nearest hour).
 
   const secondsToMinutesRoundedDown = [
     [0, 0],
@@ -351,17 +352,16 @@ contract('Fee arithmetic tests', async accounts => {
   })
 
   it("minutesPassedSinceLastFeeOp(): returns minutes passed between time of last fee operation and current block.timestamp, rounded down to nearest minutes", async () => {
-    for (testPair of secondsToMinutesRoundedDown) {
+    for (const [seconds, expectedMinutesPassed] of secondsToMinutesRoundedDown) {
       await troveManagerTester.setLastFeeOpTimeToNow()
 
-      const seconds = testPair[0]
-      const expectedHoursPassed = testPair[1]
-
-      await th.fastForwardTime(seconds, web3.currentProvider)
+      if (seconds > 0) {
+        await time.increase(seconds)
+      }
 
       const minutesPassed = await troveManagerTester.minutesPassedSinceLastFeeOp()
 
-      assert.equal(expectedHoursPassed.toString(), minutesPassed.toString())
+      assert.equal(expectedMinutesPassed.toString(), minutesPassed.toString())
     }
   })
 

contracts/test/StabilityPoolTest.js

@@ -1,3 +1,4 @@
+const { time } = require('@nomicfoundation/hardhat-network-helpers');
 const deploymentHelper = require("../utils/deploymentHelpers.js");
 const testHelpers = require("../utils/testHelpers.js");
 const { fundAccounts } = require("../utils/fundAccounts.js");
@@ -1102,10 +1103,7 @@ contract("StabilityPool", async (accounts) => {
       await stabilityPool.provideToSP(dec(105, 18), { from: D });
 
       // time passes
-      await th.fastForwardTime(
-        timeValues.SECONDS_IN_ONE_HOUR,
-        web3.currentProvider
-      );
+      await time.increase(timeValues.SECONDS_IN_ONE_HOUR);
 
       // B deposits
       await stabilityPool.provideToSP(dec(5, 18), { from: B });
@@ -2210,10 +2208,7 @@ contract("StabilityPool", async (accounts) => {
         await th.ICRbetween100and110(defaulter_1_TroveId, troveManager, price)
       );
 
-      await th.fastForwardTime(
-        timeValues.MINUTES_IN_ONE_WEEK,
-        web3.currentProvider
-      );
+      await time.increase(timeValues.MINUTES_IN_ONE_WEEK);
 
       // Liquidate d1
       await troveManager.liquidate(defaulter_1_TroveId);
@@ -2897,10 +2892,7 @@ contract("StabilityPool", async (accounts) => {
       await stabilityPool.provideToSP(dec(10000, 18), { from: E });
 
       // Fast-forward time and make a second deposit
-      await th.fastForwardTime(
-        timeValues.SECONDS_IN_ONE_HOUR,
-        web3.currentProvider
-      );
+      await time.increase(timeValues.SECONDS_IN_ONE_HOUR);
       await stabilityPool.provideToSP(dec(10000, 18), { from: E });
 
       // perform a liquidation to make 0 < P < 1, and S > 0
@@ -3008,10 +3000,7 @@ contract("StabilityPool", async (accounts) => {
       //  SETUP: Execute a series of operations to trigger ETH rewards for depositor A
 
       // Fast-forward time and make a second deposit
-      await th.fastForwardTime(
-        timeValues.SECONDS_IN_ONE_HOUR,
-        web3.currentProvider
-      );
+      await time.increase(timeValues.SECONDS_IN_ONE_HOUR);
       await stabilityPool.provideToSP(dec(100, 18), { from: A });
 
       // perform a liquidation to make 0 < P < 1, and S > 0
@@ -3711,10 +3700,7 @@ contract("StabilityPool", async (accounts) => {
       await stabilityPool.provideToSP(dec(40, 18), { from: D });
 
       // fastforward time, and E makes a deposit
-      await th.fastForwardTime(
-        timeValues.SECONDS_IN_ONE_HOUR,
-        web3.currentProvider
-      );
+      await time.increase(timeValues.SECONDS_IN_ONE_HOUR);
       await openTrove({
         extraBoldAmount: toBN(dec(3000, 18)),
         ICR: toBN(dec(2, 18)),