Fix e2e transfer test flakiness due to epoch rewards

packages/celotool/src/e2e-tests/transfer_tests.ts

@@ -1,6 +1,6 @@
 // tslint:disable-next-line: no-reference (Required to make this work w/ ts-node)
 import { CeloTxPending, CeloTxReceipt, TransactionResult } from '@celo/connect'
-import { CeloContract, ContractKit, newKitFromWeb3 } from '@celo/contractkit'
+import { ContractKit, newKitFromWeb3 } from '@celo/contractkit'
 import { CeloTokenType, EachCeloToken, StableToken, Token } from '@celo/contractkit/lib/celo-tokens'
 import { eqAddress } from '@celo/utils/lib/address'
 import { toFixed } from '@celo/utils/lib/fixidity'
@@ -158,13 +158,13 @@ describe('Transfer tests', function (this: any) {
 
   let currentGethInstance: GethInstanceConfig
 
+  let governanceAddress: string // set later on using the contract itself
   const validatorAddress = '0x47e172f6cfb6c7d01c1574fa3e2be7cc73269d95'
   const DEF_FROM_PK = 'f2f48ee19680706196e2e339e5da3491186e0c4c5030670656b0e0164837257d'
   const FromAddress = '0x5409ed021d9299bf6814279a6a1411a7e866a631'
 
   // Arbitrary addresses.
   const txFeeRecipientAddress = '0x5555555555555555555555555555555555555555'
-  const governanceAddress = '0x00000000000000000000000000000000DeaDBeef'
   const ToAddress = '0xbBae99F0E1EE565404465638d40827b54D343638'
   const gatewayFeeRecipientAddress = '0x4f5f8a3f45d179553e7b95119ce296010f50f6f1'
 
@@ -239,13 +239,17 @@ describe('Transfer tests', function (this: any) {
       3
     )
 
-    // Install an arbitrary address as the goverance address to act as the infrastructure fund.
-    // This is chosen instead of full migration for speed and to avoid the need for a governance
-    // proposal, as all contracts are owned by governance once the migration is complete.
-    const registry = await kit._web3Contracts.getRegistry()
-    const tx = registry.methods.setAddressFor(CeloContract.Governance, governanceAddress)
-    const gas = await tx.estimateGas({ from: validatorAddress })
-    await tx.send({ from: validatorAddress, gas })
+    governanceAddress = (await kit._web3Contracts.getGovernance()).options.address
+    // The tests below check the balance of the governance contract (i.e. the community fund)
+    // before and after transactions to verify the correct amount has been received from the fees.
+    // This causes flakiness due to the fund also receiving epoch rewards (if the epoch change is
+    // between the blocks the balance checker uses as its before and after the test will fail due
+    // to the unexpected change from the epoch rewards).
+    // To avoid this, we set the community fund's fraction of epoch rewards to zero.
+    // Another option would have been to make the epoch size large enough so no epoch changes happen
+    // during the test.
+    const epochRewards = await kit._web3Contracts.getEpochRewards()
+    await epochRewards.methods.setCommunityRewardFraction(0).send({ from: validatorAddress })
 
     // Give the account we will send transfers as sufficient gold and dollars.
     const startBalance = TransferAmount.times(500)