op-e2e: Load logs from the receipts instead of rescanning entire chain (#8739)

Avoids flakiness if the client's event index hasn't been updated yet.

op-e2e/bridge_test.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/ethereum-optimism/optimism/op-bindings/bindings"
 	"github.com/ethereum-optimism/optimism/op-bindings/predeploys"
+	"github.com/ethereum-optimism/optimism/op-e2e/e2eutils/receipts"
 	"github.com/ethereum-optimism/optimism/op-e2e/e2eutils/transactions"
 	"github.com/ethereum-optimism/optimism/op-e2e/e2eutils/wait"
 	"github.com/ethereum-optimism/optimism/op-node/rollup/derive"
@@ -63,17 +64,11 @@ func TestERC20BridgeDeposits(t *testing.T) {
 	require.NoError(t, err)
 	tx, err = optimismMintableTokenFactory.CreateOptimismMintableERC20(l2Opts, weth9Address, "L2-WETH", "L2-WETH")
 	require.NoError(t, err)
-	_, err = wait.ForReceiptOK(context.Background(), l2Client, tx.Hash())
+	rcpt, err := wait.ForReceiptOK(context.Background(), l2Client, tx.Hash())
 	require.NoError(t, err)
 
-	// Get the deployment event to have access to the L2 WETH9 address
-	it, err := optimismMintableTokenFactory.FilterOptimismMintableERC20Created(&bind.FilterOpts{Start: 0}, nil, nil)
-	require.NoError(t, err)
-	var event *bindings.OptimismMintableERC20FactoryOptimismMintableERC20Created
-	for it.Next() {
-		event = it.Event
-	}
-	require.NotNil(t, event)
+	event, err := receipts.FindLog(rcpt.Logs, optimismMintableTokenFactory.ParseOptimismMintableERC20Created)
+	require.NoError(t, err, "Should emit ERC20Created event")
 
 	// Approve WETH9 with the bridge
 	tx, err = WETH9.Approve(opts, cfg.L1Deployments.L1StandardBridgeProxy, new(big.Int).SetUint64(math.MaxUint64))
@@ -97,13 +92,8 @@ func TestERC20BridgeDeposits(t *testing.T) {
 	portal, err := bindings.NewOptimismPortal(cfg.L1Deployments.OptimismPortalProxy, l1Client)
 	require.NoError(t, err)
 
-	depIt, err := portal.FilterTransactionDeposited(&bind.FilterOpts{Start: 0}, nil, nil, nil)
-	require.NoError(t, err)
-	var depositEvent *bindings.OptimismPortalTransactionDeposited
-	for depIt.Next() {
-		depositEvent = depIt.Event
-	}
-	require.NotNil(t, depositEvent)
+	depositEvent, err := receipts.FindLog(depositReceipt.Logs, portal.ParseTransactionDeposited)
+	require.NoError(t, err, "Should emit deposit event")
 
 	depositTx, err := derive.UnmarshalDepositLogEvent(&depositEvent.Raw)
 	require.NoError(t, err)

op-e2e/e2eutils/receipts/logs.go

+package receipts
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/core/types"
+)
+
+// FindLog searches the array of logs (typically retrieved from a receipt) to find one that can be parsed by the
+// supplied parser (usually the Parse<EventName> function from generated bindings for a contract).
+// e.g. receipts.FindLog(receipt.Logs, optimismPortal.ParseTransactionDeposited)
+// Either the first parsable event is returned or an error with the parse failures.
+func FindLog[T any](logs []*types.Log, parser func(types.Log) (T, error)) (T, error) {
+	var errs error
+	for i, l := range logs {
+		parsed, err := parser(*l)
+		if err == nil {
+			return parsed, nil
+		}
+		errs = errors.Join(errs, fmt.Errorf("parse log %v: %w", i, err))
+	}
+	var noMatch T
+	return noMatch, fmt.Errorf("no matching log found: %w", errs)
+}