ethclient/simulated: add goroutine leak test (#31033)

Adds a basic sanity test case to catch any go-routines leaked from
instantiation/closing of a simulated backend.

Author: jwasinger

ethclient/simulated/backend_test.go

@@ -25,6 +25,8 @@ import (
 	"testing"
 	"time"
 
+	"go.uber.org/goleak"
+
 	"github.com/ethereum/go-ethereum/crypto/kzg4844"
 	"github.com/holiman/uint256"
 
@@ -350,3 +352,20 @@ func TestAdjustTimeAfterFork(t *testing.T) {
 		t.Errorf("failed to build block on fork")
 	}
 }
+
+func createAndCloseSimBackend() {
+	genesisData := types.GenesisAlloc{}
+	simulatedBackend := NewBackend(genesisData)
+	defer simulatedBackend.Close()
+}
+
+// TestCheckSimBackendGoroutineLeak checks whether creation of a simulated backend leaks go-routines.  Any long-lived go-routines
+// spawned by global variables are not considered leaked.
+func TestCheckSimBackendGoroutineLeak(t *testing.T) {
+	createAndCloseSimBackend()
+	ignoreCur := goleak.IgnoreCurrent()
+	// ignore this leveldb function:  this go-routine is guaranteed to be terminated 1 second after closing db handle
+	ignoreLdb := goleak.IgnoreAnyFunction("github.com/syndtr/goleveldb/leveldb.(*DB).mpoolDrain")
+	createAndCloseSimBackend()
+	goleak.VerifyNone(t, ignoreCur, ignoreLdb)
+}

go.mod

@@ -63,6 +63,7 @@ require (
 	github.com/syndtr/goleveldb v1.0.1-0.20210819022825-2ae1ddf74ef7
 	github.com/urfave/cli/v2 v2.27.5
 	go.uber.org/automaxprocs v1.5.2
+	go.uber.org/goleak v1.3.0
 	golang.org/x/crypto v0.32.0
 	golang.org/x/exp v0.0.0-20231110203233-9a3e6036ecaa
 	golang.org/x/sync v0.10.0

go.sum

@@ -528,6 +528,8 @@ go.opencensus.io v0.22.3/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.opencensus.io v0.22.4/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.uber.org/automaxprocs v1.5.2 h1:2LxUOGiR3O6tw8ui5sZa2LAaHnsviZdVOUZw4fvbnME=
 go.uber.org/automaxprocs v1.5.2/go.mod h1:eRbA25aqJrxAbsLO0xy5jVwPt7FQnRgjW+efnwa1WM0=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
+go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=