test: Add integration test for UsePubSubEmulatorExample

.github/workflows/java-pubsub-integration-tests-against-emulator.yaml

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+# 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.
+
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+name: java-pubsub integration-tests-against-emulator
+jobs:
+  filter:
+    runs-on: ubuntu-latest
+    outputs:
+      library: ${{ steps.filter.outputs.library }}
+    steps:
+    - uses: actions/checkout@v6
+    - uses: dorny/paths-filter@v4
+      id: filter
+      with:
+        filters: |
+          library:
+            - 'java-pubsub/**'
+  integration-tests:
+    needs: filter
+    if: ${{ needs.filter.outputs.library == 'true' }}
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v6
+    - uses: actions/setup-java@v5
+      with:
+        distribution: temurin
+        java-version: 17
+    - name: Start Pub/Sub Emulator
+      run: |
+        docker run -d -p 8085:8085 --name pubsub-emulator gcr.io/google.com/cloudsdktool/cloud-sdk:567.0.0-emulators gcloud beta emulators pubsub start --project=abc --host-port=0.0.0.0:8085
+        echo "Waiting for emulator to start..."
+        sleep 10
+
+    - name: Running tests
+      run: .kokoro/build.sh
+      env:
+        JOB_TYPE: test
+        BUILD_SUBDIR: java-pubsub
+        PUBSUB_EMULATOR_HOST: localhost:8085
+        GOOGLE_CLOUD_PROJECT: abc
+        SUREFIRE_JVM_OPT: '-Dtest=UsePubSubEmulatorExampleIT -Dsurefire.failIfNoSpecifiedTests=false'

java-pubsub/samples/snippets/src/test/java/pubsub/UsePubSubEmulatorExampleIT.java

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+/*
+ * 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.
+ */
+
+package pubsub;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth.assertWithMessage;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class UsePubSubEmulatorExampleIT {
+  private ByteArrayOutputStream bout;
+  private PrintStream out;
+  private PrintStream originalOut;
+
+  private static void requireEnvVar(String varName) {
+    assertWithMessage("Environment variable " + varName + " is required to perform these tests.")
+        .that(System.getenv(varName))
+        .isNotNull();
+  }
+
+  @BeforeClass
+  public static void checkRequirements() {
+    requireEnvVar("PUBSUB_EMULATOR_HOST");
+  }
+
+  @Before
+  public void setUp() {
+    originalOut = System.out;
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    System.setOut(out);
+  }
+
+  @After
+  public void tearDown() {
+    System.setOut(originalOut);
+  }
+
+  @Test
+  public void testUsePubSubEmulatorExample() throws Exception {
+    UsePubSubEmulatorExample.main();
+    String output = bout.toString();
+    assertThat(output).contains("Created topic: ");
+    assertThat(output).contains("Published message ID: ");
+  }
+}