chore(pubsub/v2): use client hooks for emulator (#14487)

Fixes #10577

Author: hongalex

pubsub/v2/apiv1/emulator_hook.go

@@ -0,0 +1,44 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package pubsub
+
+import (
+	"context"
+	"os"
+
+	"google.golang.org/api/option"
+	"google.golang.org/api/option/internaloption"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+func init() {
+	newTopicAdminClientHook = emulatorHook
+	newSubscriptionAdminClientHook = emulatorHook
+	newSchemaClientHook = emulatorHook
+}
+
+func emulatorHook(ctx context.Context, params clientHookParams) ([]option.ClientOption, error) {
+	if addr := os.Getenv("PUBSUB_EMULATOR_HOST"); addr != "" {
+		return []option.ClientOption{
+			option.WithEndpoint(addr),
+			option.WithGRPCDialOption(grpc.WithTransportCredentials(insecure.NewCredentials())),
+			option.WithoutAuthentication(),
+			option.WithTelemetryDisabled(),
+			internaloption.SkipDialSettingsValidation(),
+		}, nil
+	}
+	return nil, nil
+}

pubsub/v2/pubsub.go

@@ -29,9 +29,7 @@ import (
 	"cloud.google.com/go/pubsub/v2/internal"
 	gax "github.com/googleapis/gax-go/v2"
 	"google.golang.org/api/option"
-	"google.golang.org/api/option/internaloption"
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/keepalive"
 )
 
@@ -168,18 +166,7 @@ func NewClientWithConfig(ctx context.Context, projectID string, config *ClientCo
 		return nil, ErrEmptyProjectID
 	}
 	var o []option.ClientOption
-	// Environment variables for gcloud emulator:
-	// https://cloud.google.com/sdk/gcloud/reference/beta/emulators/pubsub/
-	if addr := os.Getenv("PUBSUB_EMULATOR_HOST"); addr != "" {
-		emulatorOpts := []option.ClientOption{
-			option.WithEndpoint(addr),
-			option.WithGRPCDialOption(grpc.WithTransportCredentials(insecure.NewCredentials())),
-			option.WithoutAuthentication(),
-			option.WithTelemetryDisabled(),
-			internaloption.SkipDialSettingsValidation(),
-		}
-		opts = append(emulatorOpts, opts...)
-	} else {
+	if os.Getenv("PUBSUB_EMULATOR_HOST") == "" {
 		numConns := runtime.GOMAXPROCS(0)
 		if numConns > 4 {
 			numConns = 4