Add an ERC20 fee currency for testing purposes (#71)

* Add an ERC20 gas token for testing purposes

This is a copy of OpenZeppelin's ERC20 with added credit/debitGasFees
functions. Inheriting from ERC20 does not work due to the need to access
the private _balances and _totalSupply fields.

* lint fix

* Initialize FeeCurrency

* test fix

* immutables test fix

* duplicate removal

* Change address

* test fixes

* another test fix

---------

Co-authored-by: pahor167 <47992132+pahor167@users.noreply.github.com>

op-bindings/artifacts.json

@@ -48,5 +48,6 @@
   "MentoFeeHandlerSeller",
   "UniswapFeeHandlerSeller",
   "SortedOracles",
-  "AddressSortedLinkedListWithMedian"
+  "AddressSortedLinkedListWithMedian",
+  "FeeCurrency"
 ]

op-bindings/predeploys/addresses.go

@@ -34,6 +34,7 @@ const (
 	UniswapFeeHandlerSeller           = "0xd3aee28548dbb65df03981f0dc0713bfcbd10a97"
 	SortedOracles                     = "0xefb84935239dacdecf7c5ba76d8de40b077b7b33"
 	AddressSortedLinkedListWithMedian = "0xED477A99035d0c1e11369F1D7A4e587893cc002B"
+	FeeCurrency                       = "0x4200000000000000000000000000000000001022"
 )
 
 var (
@@ -65,6 +66,7 @@ var (
 	UniswapFeeHandlerSellerAddr           = common.HexToAddress(UniswapFeeHandlerSeller)
 	SortedOraclesAddr                     = common.HexToAddress(SortedOracles)
 	AddressSortedLinkedListWithMedianAddr = common.HexToAddress(AddressSortedLinkedListWithMedian)
+	FeeCurrencyAddr                       = common.HexToAddress(FeeCurrency)
 
 	Predeploys     = make(map[string]*common.Address)
 	CeloPredeploys = make(map[string]*common.Address)
@@ -112,6 +114,7 @@ func init() {
 	Predeploys["UniswapFeeHandlerSeller"] = &UniswapFeeHandlerSellerAddr
 	Predeploys["SortedOracles"] = &SortedOraclesAddr
 	Predeploys["AddressSortedLinkedListWithMedian"] = &AddressSortedLinkedListWithMedianAddr
+	Predeploys["FeeCurrency"] = &FeeCurrencyAddr
 
 	CeloPredeploys[Predeploys["CeloRegistry"].String()] = Predeploys["CeloRegistry"]
 	CeloPredeploys[Predeploys["GoldToken"].String()] = Predeploys["GoldToken"]
@@ -121,4 +124,5 @@ func init() {
 	CeloPredeploys[Predeploys["UniswapFeeHandlerSeller"].String()] = Predeploys["UniswapFeeHandlerSeller"]
 	CeloPredeploys[Predeploys["SortedOracles"].String()] = Predeploys["SortedOracles"]
 	CeloPredeploys[Predeploys["AddressSortedLinkedListWithMedian"].String()] = Predeploys["AddressSortedLinkedListWithMedian"]
+	CeloPredeploys[Predeploys["FeeCurrency"].String()] = Predeploys["FeeCurrency"]
 }

op-chain-ops/genesis/config.go

@@ -674,6 +674,10 @@ func NewL2ImmutableConfig(config *DeployConfig, block *types.Block) (immutables.
 		"minimumWithdrawalAmount": config.BaseFeeVaultMinimumWithdrawalAmount,
 		"withdrawalNetwork":       config.BaseFeeVaultWithdrawalNetwork.ToUint8(),
 	}
+	immutable["FeeCurrency"] = immutables.ImmutableValues{
+		"name":   "FeeCurrency",
+		"symbol": "FC",
+	}
 
 	return immutable, nil
 }
@@ -779,6 +783,14 @@ func NewL2StorageConfig(config *DeployConfig, block *types.Block) (state.Storage
 		"_owner":              config.ProxyAdminOwner,
 		"reportExpirySeconds": 600,
 	}
+	storage["FeeCurrency"] = state.StorageValues{
+		"_name":        "FeeCurrency",
+		"_symbol":      "FC",
+		"_totalSupply": 1000_000_000,
+		"_balances": map[any]any{
+			config.ProxyAdminOwner.String(): 1000_000_000,
+		},
+	}
 	return storage, nil
 }
 

op-chain-ops/genesis/layer_two_test.go

@@ -85,7 +85,7 @@ func TestBuildL2MainnetGenesis(t *testing.T) {
 	config.EnableGovernance = true
 	config.FundDevAccounts = false
 	gen := testBuildL2Genesis(t, config)
-	require.Equal(t, 2337, len(gen.Alloc))
+	require.Equal(t, 2339, len(gen.Alloc))
 }
 
 func TestBuildL2MainnetNoGovernanceGenesis(t *testing.T) {
@@ -94,5 +94,5 @@ func TestBuildL2MainnetNoGovernanceGenesis(t *testing.T) {
 	config.EnableGovernance = false
 	config.FundDevAccounts = false
 	gen := testBuildL2Genesis(t, config)
-	require.Equal(t, 2337, len(gen.Alloc))
+	require.Equal(t, 2339, len(gen.Alloc))
 }

op-chain-ops/immutables/immutables.go

@@ -196,6 +196,12 @@ func BuildOptimism(immutable ImmutableConfig) (DeploymentResults, error) {
 			Name: "AddressSortedLinkedListWithMedian",
 			Args: []interface{}{},
 		},
+		{
+			Name: "FeeCurrency",
+			Args: []interface{}{
+				immutable["FeeCurrency"]["name"], immutable["FeeCurrency"]["symbol"], immutable["FeeCurrency"]["mintTo"],
+			},
+		},
 	}
 	return BuildL2(deployments)
 }
@@ -307,6 +313,16 @@ func l2Deployer(backend *backends.SimulatedBackend, opts *bind.TransactOpts, dep
 		_, tx, _, err = bindings.DeploySortedOracles(opts, backend, false)
 	case "AddressSortedLinkedListWithMedian":
 		_, tx, _, err = bindings.DeployAddressSortedLinkedListWithMedian(opts, backend)
+	case "FeeCurrency":
+		name, ok := deployment.Args[0].(string)
+		if !ok {
+			return nil, fmt.Errorf("invalid fee currency name")
+		}
+		symbol, ok := deployment.Args[1].(string)
+		if !ok {
+			return nil, fmt.Errorf("invalid fee currency symbol")
+		}
+		_, tx, _, err = bindings.DeployFeeCurrency(opts, backend, name, symbol)
 	default:
 		return tx, fmt.Errorf("unknown contract: %s", deployment.Name)
 	}

op-chain-ops/immutables/immutables_test.go

@@ -83,6 +83,10 @@ func TestBuildOptimism(t *testing.T) {
 			"minimumWithdrawalAmount": minimumWithdrawalAmount,
 			"withdrawalNetwork":       uint8(0),
 		},
+		"FeeCurrency": {
+			"name":   "FeeCurrency",
+			"symbol": "FC",
+		},
 	})
 	require.Nil(t, err)
 	require.NotNil(t, results)
@@ -113,6 +117,7 @@ func TestBuildOptimism(t *testing.T) {
 		"UniswapFeeHandlerSeller":           true,
 		"SortedOracles":                     true,
 		"AddressSortedLinkedListWithMedian": true,
+		"FeeCurrency":                       true,
 	}
 
 	// Only the exact contracts that we care about are being