PR fixes

driver-core/src/main/com/mongodb/connection/AsyncTransportSettings.java

@@ -17,15 +17,20 @@
  */
 package com.mongodb.connection;
 
+import com.mongodb.annotations.Immutable;
 import com.mongodb.lang.Nullable;
 
+import java.nio.channels.AsynchronousChannelGroup;
 import java.util.concurrent.ExecutorService;
 
+import static com.mongodb.assertions.Assertions.notNull;
+
 /**
  * {@link TransportSettings} for a non-<a href="http://netty.io/">Netty</a>-based async transport implementation.
  *
  * @since 5.2
  */
+@Immutable
 public final class AsyncTransportSettings extends TransportSettings {
 
     private final ExecutorService executorService;
@@ -49,15 +54,16 @@ private Builder() {
         }
 
         /**
-         * Sets the executor service
+         * Sets the executor service. This executor service will not be shut
+         * down by the driver code, and must be shut down by application code.
          *
          * @param executorService the executor service
          * @return this
          * @see #getExecutorService()
          * @see AsynchronousChannelGroup#withThreadPool(ExecutorService)
          */
         public Builder executorService(final ExecutorService executorService) {
-            this.executorService = executorService;
+            this.executorService = notNull("executorService", executorService);
             return this;
         }
 
@@ -80,4 +86,11 @@ public AsyncTransportSettings build() {
     public ExecutorService getExecutorService() {
         return executorService;
     }
+
+    @Override
+    public String toString() {
+        return "AsyncTransportSettings{" +
+                "executorService=" + executorService +
+                '}';
+    }
 }

driver-core/src/main/com/mongodb/internal/connection/StreamFactoryHelper.java

@@ -38,7 +38,7 @@ public static StreamFactory getSyncStreamFactory(final MongoClientSettings setti
         if (transportSettings == null) {
             return new SocketStreamFactory(inetAddressResolver, socketSettings, settings.getSslSettings());
         } else if (transportSettings instanceof AsyncTransportSettings) {
-            throw new MongoClientException("Unsupported async transport settings: " + transportSettings.getClass().getName());
+            throw new MongoClientException("Unsupported transport settings in sync: " + transportSettings.getClass().getName());
         } else if (transportSettings instanceof NettyTransportSettings) {
             return getNettyStreamFactoryFactory(inetAddressResolver, (NettyTransportSettings) transportSettings)
                     .create(socketSettings, settings.getSslSettings());

driver-core/src/test/unit/com/mongodb/connection/AsyncTransportSettingsTest.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2008-present MongoDB, Inc.
+ *
+ * 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 com.mongodb.connection;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+class AsyncTransportSettingsTest {
+
+    @Test
+    public void shouldDefaultAllValuesToNull() {
+        AsyncTransportSettings settings = TransportSettings.asyncBuilder().build();
+
+        assertNull(settings.getExecutorService());
+    }
+
+    @Test
+    public void shouldApplySettingsFromBuilder() {
+        ExecutorService executorService = Executors.newFixedThreadPool(1);
+        AsyncTransportSettings settings = TransportSettings.asyncBuilder()
+                .executorService(executorService)
+                .build();
+
+        assertEquals(executorService, settings.getExecutorService());
+    }
+}

driver-reactive-streams/src/test/functional/com/mongodb/reactivestreams/client/AsyncTransportSettingsTest.java

@@ -27,44 +27,44 @@
 import java.util.concurrent.Executors;
 
 import static com.mongodb.client.Fixture.getMongoClientSettingsBuilder;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.atLeastOnce;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.verify;
 
 class AsyncTransportSettingsTest {
-    @Test
-    public void shouldDefaultAllValuesToNull() {
-        AsyncTransportSettings settings = TransportSettings.asyncBuilder().build();
-
-        assertNull(settings.getExecutorService());
-    }
 
     @Test
-    public void shouldApplySettingsFromBuilder() {
-        ExecutorService executorService = Executors.newFixedThreadPool(1);
-        AsyncTransportSettings settings = TransportSettings.asyncBuilder()
+    void testAsyncTransportSettings() {
+        ExecutorService executorService = spy(Executors.newFixedThreadPool(5));
+        AsyncTransportSettings asyncTransportSettings = TransportSettings.asyncBuilder()
                 .executorService(executorService)
                 .build();
+        MongoClientSettings mongoClientSettings = getMongoClientSettingsBuilder()
+                .transportSettings(asyncTransportSettings)
+                .build();
 
-        assertEquals(executorService, settings.getExecutorService());
+        try (MongoClient client = new SyncMongoClient(MongoClients.create(mongoClientSettings))) {
+            client.listDatabases().first();
+        }
+        verify(executorService, atLeastOnce()).execute(any());
     }
 
     @Test
-    void testAsyncTransportSettings() {
+    void testExternalExecutorNotShutDown() {
         ExecutorService executorService = spy(Executors.newFixedThreadPool(5));
         AsyncTransportSettings asyncTransportSettings = TransportSettings.asyncBuilder()
                 .executorService(executorService)
                 .build();
         MongoClientSettings mongoClientSettings = getMongoClientSettingsBuilder()
+                .applyToSslSettings(builder -> builder.enabled(true))
                 .transportSettings(asyncTransportSettings)
                 .build();
 
-        try (MongoClient client = new SyncMongoClient(MongoClients.create(mongoClientSettings))) {
-            client.listDatabases().first();
+        try (MongoClient ignored = new SyncMongoClient(MongoClients.create(mongoClientSettings))) {
+            // ignored
         }
-        verify(executorService, atLeastOnce()).execute(any());
+        verify(executorService, never()).shutdown();
     }
 }