chore(pubsub): Add samples for topic and subscription SMTs (#32791)

Author: aandreassa

google-cloud-pubsub/samples/acceptance/subscriptions_test.rb

@@ -33,6 +33,7 @@
 require_relative "../pubsub_test_subscription_permissions.rb"
 require_relative "../pubsub_detach_subscription.rb"
 require_relative "../pubsub_delete_subscription.rb"
+require_relative "../pubsub_create_subscription_with_smt.rb"
 require "google/cloud/bigquery"
 
 describe "subscriptions" do
@@ -266,6 +267,18 @@
     end
   end 
 
+  it "supports creating subscription with SMT" do
+    project_id = pubsub.project
+    topic_id = @topic.name
+    subscription_id = random_subscription_id
+    @created_subscriptions << subscription_id
+
+    assert_output "Created subscription with SMT: projects/#{pubsub.project}/subscriptions/#{subscription_id}\n" do     
+      create_subscription_with_smt topic_id: topic_id,
+                                   subscription_id: subscription_id
+    end
+  end
+
   it "supports creating bigquery subscription" do
     project_id = pubsub.project
     topic_id = @topic.name

google-cloud-pubsub/samples/acceptance/topics_test.rb

@@ -45,6 +45,7 @@
 require_relative "../pubsub_test_topic_permissions.rb"
 require_relative "../pubsub_update_topic_type.rb"
 require_relative "../pubsub_create_topic_with_schema_revisions.rb"
+require_relative "../pubsub_create_topic_with_smt.rb"
 
 describe "emulator" do
   let(:pubsub) { Google::Cloud::Pubsub.new }
@@ -141,6 +142,13 @@
     end
   end
 
+  it "supports pubsub_create_topic_with_smt" do
+    # pubsub_create_topic_with_smt
+    assert_output "Created topic with SMT: projects/#{pubsub.project}/topics/#{topic_id}\n" do
+      create_topic_with_smt topic_id: topic_id
+    end
+  end
+
   it "supports pubsub_create_topic, pubsub_create_cloud_storage_subscription" do
     # pubsub_create_topic
     assert_output "Topic projects/#{pubsub.project}/topics/#{topic_id} created.\n" do

google-cloud-pubsub/samples/pubsub_create_subscription_with_smt.rb

@@ -0,0 +1,48 @@
+# 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
+#
+#     http://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.
+
+require "google/cloud/pubsub"
+
+def create_subscription_with_smt topic_id:, subscription_id:
+  # [START pubsub_create_subscription_with_smt]
+  # topic_id        = "your-topic-id"
+  # subscription_id = "your-subscription-id"
+
+  pubsub = Google::Cloud::PubSub.new
+  subscription_admin = pubsub.subscription_admin
+
+  # UDF that removes the 'ssn' field, if present
+  code = "function redactSSN(message, metadata) {\n" \
+         "  const data = JSON.parse(message.data);\n" \
+         "  delete data['ssn'];\n" \
+         "  message.data = JSON.stringify(data);\n" \
+         "  return message;\n" \
+         "}"
+
+  subscription = subscription_admin.create_subscription(
+    name: pubsub.subscription_path(subscription_id),
+    topic: pubsub.topic_path(topic_id),
+    message_transforms: [
+      {
+        javascript_udf: {
+          function_name: "redactSSN",
+          code: code
+        }
+      }
+    ]
+  )
+
+  puts "Created subscription with SMT: #{subscription.name}"
+  # [END pubsub_create_subscription_with_smt]
+end

google-cloud-pubsub/samples/pubsub_create_topic_with_smt.rb

@@ -0,0 +1,46 @@
+# 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
+#
+#     http://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.
+
+require "google/cloud/pubsub"
+
+def create_topic_with_smt topic_id:
+  # [START pubsub_create_topic_with_smt]
+  # topic_id = "your-topic-id"
+
+  pubsub = Google::Cloud::PubSub.new
+  topic_admin = pubsub.topic_admin
+
+  # UDF that removes the 'ssn' field, if present
+  code = "function redactSSN(message, metadata) {\n" \
+         "  const data = JSON.parse(message.data);\n" \
+         "  delete data['ssn'];\n" \
+         "  message.data = JSON.stringify(data);\n" \
+         "  return message;\n" \
+         "}"
+
+  topic = topic_admin.create_topic(
+    name: pubsub.topic_path(topic_id),
+    message_transforms: [
+      {
+        javascript_udf: {
+          function_name: "redactSSN",
+          code: code
+        }
+      }
+    ]
+  )
+
+  puts "Created topic with SMT: #{topic.name}"
+  # [END pubsub_create_topic_with_smt]
+end