samples: subscription detachment (#289)

* samples: subscription detachment

* nit: println

* remove dlq policy

samples/snippets/src/main/java/pubsub/DetachSubscriptionExample.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2020 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;
+
+// [START pubsub_detach_subscription]
+import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
+import com.google.cloud.pubsub.v1.TopicAdminClient;
+import com.google.pubsub.v1.DetachSubscriptionRequest;
+import com.google.pubsub.v1.ProjectSubscriptionName;
+import com.google.pubsub.v1.Subscription;
+import java.io.IOException;
+
+public class DetachSubscriptionExample {
+  public static void main(String... args) throws Exception {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectId = "your-project-id";
+    // Choose an existing subscription.
+    String subscriptionId = "your-subscription-id";
+
+    detachSubscriptionExample(projectId, subscriptionId);
+  }
+
+  public static void detachSubscriptionExample(String projectId, String subscriptionId)
+      throws IOException {
+    ProjectSubscriptionName subscriptionName =
+        ProjectSubscriptionName.of(projectId, subscriptionId);
+
+    try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
+      topicAdminClient.detachSubscription(
+          DetachSubscriptionRequest.newBuilder()
+              .setSubscription(subscriptionName.toString())
+              .build());
+    }
+
+    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
+      Subscription subscription = subscriptionAdminClient.getSubscription(subscriptionName);
+      if (subscription.getDetached()) {
+        System.out.println("Subscription is detached.");
+      } else {
+        System.out.println("Subscription is NOT detached.");
+      }
+    }
+  }
+}
+// [END pubsub_detach_subscription]

samples/snippets/src/main/java/pubsub/RemoveDeadLetterPolicyExample.java

@@ -46,9 +46,6 @@ public static void removeDeadLetterPolicyExample(
           ProjectSubscriptionName.of(projectId, subscriptionId);
       TopicName topicName = TopicName.of(projectId, topicId);
 
-      System.out.println(
-          "Before: " + subscriptionAdminClient.getSubscription(subscriptionName).getAllFields());
-
       // Construct the subscription you expect to have after the request. Here,
       // values in the required fields (name, topic) help identify the subscription.
       // No dead letter policy is supplied.
@@ -61,9 +58,7 @@ public static void removeDeadLetterPolicyExample(
       // Construct a field mask to indicate which field to update in the subscription.
       FieldMask updateMask =
           FieldMask.newBuilder()
-              .addPaths("dead_letter_policy.dead_letter_topic")
-              // A default of 5 is applied upon successful update.
-              .addPaths("dead_letter_policy.max_delivery_attempts")
+              .addPaths("dead_letter_policy")
               .build();
 
       UpdateSubscriptionRequest request =

samples/snippets/src/test/java/pubsub/AdminIT.java

@@ -169,13 +169,19 @@ public void testAdmin() throws Exception {
     assertThat(bout.toString()).contains("permissions: \"pubsub.subscriptions.consume\"");
     assertThat(bout.toString()).contains("permissions: \"pubsub.subscriptions.update\"");
 
+    bout.reset();
+    // Test subscription detachment.
+    DetachSubscriptionExample.detachSubscriptionExample(projectId, pullSubscriptionId);
+    assertThat(bout.toString()).contains("Subscription is detached.");
+
     bout.reset();
     // Test create a subscription with ordering
     CreateSubscriptionWithOrdering.createSubscriptionWithOrderingExample(
         projectId, topicId, orderedSubscriptionId);
     assertThat(bout.toString()).contains("Created a subscription with ordering");
     assertThat(bout.toString()).contains("enable_message_ordering=true");
 
+
     bout.reset();
     // Test delete subscription. Run twice to delete both pull and push subscriptions.
     DeleteSubscriptionExample.deleteSubscriptionExample(projectId, pullSubscriptionId);

samples/snippets/src/test/java/pubsub/DeadLetterQueueIT.java

@@ -138,7 +138,6 @@ public void testQuickstart() throws Exception {
     bout.reset();
     // Remove dead letter policy.
     RemoveDeadLetterPolicyExample.removeDeadLetterPolicyExample(projectId, subscriptionId, topicId);
-    assertThat(bout.toString())
-        .contains("google.pubsub.v1.Subscription.dead_letter_policy=max_delivery_attempts: 5");
+    assertThat(bout.toString()).doesNotContain("dead_letter_policy");
   }
 }