pubsub: remove obsolete doc references

This PR removes references to the deprecated code of the docs.

The emulator section is rewritten.
Example for Subscriber is missing because it still uses ChannelBuilder.
We plan to migrate it to ChannelProvider soon.

Updates #1789.

Author: pongad

README.md

@@ -585,29 +585,31 @@ Google Cloud Pub/Sub (Alpha)
 Here is a code snippet showing a simple usage example from within Compute Engine/App Engine
 Flexible. Note that you must [supply credentials](#authentication) and a project ID if running this
 snippet elsewhere. Complete source code can be found at
-[CreateSubscriptionAndPullMessages.java](./google-cloud-examples/src/main/java/com/google/cloud/examples/pubsub/snippets/CreateSubscriptionAndPullMessages.java).
+[CreateTopicAndPublishMessages.java](./google-cloud-examples/src/main/java/com/google/cloud/examples/pubsub/snippets/CreateTopicAndPublishMessages.java).
 
 ```java
-import com.google.cloud.pubsub.Message;
-import com.google.cloud.pubsub.PubSub;
-import com.google.cloud.pubsub.PubSub.MessageConsumer;
-import com.google.cloud.pubsub.PubSub.MessageProcessor;
-import com.google.cloud.pubsub.PubSubOptions;
-import com.google.cloud.pubsub.Subscription;
-import com.google.cloud.pubsub.SubscriptionInfo;
-
-try (PubSub pubsub = PubSubOptions.getDefaultInstance().getService()) {
-  Subscription subscription =
-      pubsub.create(SubscriptionInfo.of("test-topic", "test-subscription"));
-  MessageProcessor callback = new MessageProcessor() {
-    @Override
-    public void process(Message message) throws Exception {
-      System.out.printf("Received message \"%s\"%n", message.getPayloadAsString());
-    }
-  };
-  // Create a message consumer and pull messages (for 60 seconds)
-  try (MessageConsumer consumer = subscription.pullAsync(callback)) {
-    Thread.sleep(60_000);
+import com.google.api.gax.core.ApiFuture;
+import com.google.cloud.pubsub.spi.v1.Publisher;
+import com.google.cloud.pubsub.spi.v1.TopicAdminClient;
+import com.google.protobuf.ByteString;
+import com.google.pubsub.v1.PubsubMessage;
+import com.google.pubsub.v1.TopicName;
+
+TopicName topic = TopicName.create("test-project", "test-topic");
+try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
+  topicAdminClient.createTopic(topic);
+}
+
+Publisher publisher = null;
+try {
+  publisher = Publisher.newBuilder(topic).build();
+  ByteString data = ByteString.copyFromUtf8("my message");
+  PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();
+  ApiFuture<String> messageId = publisher.publish(pubsubMessage);
+  System.out.println("published with message ID: " + messageId.get());
+} finally {
+  if (publisher != null) {
+    publisher.shutdown();
   }
 }
 ```

TESTING.md

@@ -145,44 +145,34 @@ uses the `RemoteLoggingHelper` to create a metric.
 
 ### Testing code that uses Pub/Sub
 
-#### On your machine
-
-You can test against a temporary local Pub/Sub by following these steps:
-
-1. Start the local Pub/Sub emulator before running your tests using `LocalPubSubHelper`'s `create`
-and `start` methods. This will bind a port for communication with the local Pub/Sub emulator.
-  ```java
-  LocalPubSubHelper helper = LocalPubSubHelper.create();
-
-  helper.start(); // Starts the local Pub/Sub emulator in a separate process
-  ```
+You can test against a Pub/Sub emulator:
 
-2. Create and use a `PubSub` object with the options given by the `LocalPubSubHelper` instance. For
-example:
-  ```java
-  PubSub localPubsub = helper.getOptions().getService();
-  ```
-
-3. Run your tests.
+1. [Install Cloud SDK](https://cloud.google.com/sdk/downloads)
 
-4. Stop the local Pub/Sub emulator by calling the `stop()` method, like so:
-  ```java
-  helper.stop();
-  ```
-
-#### On a remote machine
-
-You can test against a remote Pub/Sub emulator as well. To do this, set the `PubSubOptions` project
-endpoint to the hostname of the remote machine, like the example below.
+2. Start the emulator:
+```shell
+$ gcloud beta emulators pubsub start
+```
 
-  ```java
-  PubSubOptions options = PubSubOptions.newBuilder()
-      .setProjectId("my-project-id") // must match project ID specified on remote machine
-      .setHost("<hostname of machine>:<port>")
-      .setCredentials(NoCredentials.getInstance())
-      .build();
-  PubSub localPubsub = options.getService();
-  ```
+3. Point your client to the emulator.
+The code below assumes that you have set the `host` and `port`
+to the host and port the emulator is on.
+```java
+ChannelProvider channelProvider =
+    // SubscriptionAdminSettings works too.
+    TopicAdminSettings.defaultChannelProviderBuilder()
+        .setServiceAddress(host)
+        .setPort(port)
+        .setCredentialsProvider(
+            FixedCredentialsProvider.create(NoCredentials.getInstance()))
+        .build();
+TopicAdminClient topicClient = TopicAdminClient.create(
+    TopicAdminSettings.defaultBuilder().setChannelProvider(channelProvider).build());
+SubscriptionAdminClient subscriptionClient = SubscriptionAdminClient.create(
+    SubscriptionAdminSettings.defaultBuilder().setChannelProvider(channelProvider).build());
+Publisher publisher =
+    Publisher.newBuilder(topicName).setChannelProvider(channelProvider).build();
+```
 
 ### Testing code that uses Resource Manager