Use @VisibleForTesting instead of writing verbose comments (#835)

Author: stIncMale

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

@@ -16,9 +16,11 @@
 
 package com.mongodb.connection;
 
+import com.mongodb.internal.VisibleForTesting;
 import org.bson.types.ObjectId;
 
 import static com.mongodb.assertions.Assertions.notNull;
+import static com.mongodb.internal.VisibleForTesting.AccessModifier.PRIVATE;
 
 /**
  * A client-generated identifier that uniquely identifies a connection to a MongoDB cluster, which could be sharded, replica set,
@@ -48,7 +50,7 @@ public ClusterId(final String description) {
         this.description = description;
     }
 
-    // for testing only, as cluster identifiers should really be unique
+    @VisibleForTesting(otherwise = PRIVATE)
     ClusterId(final String value, final String description) {
         this.value = notNull("value", value);
         this.description = description;

driver-core/src/main/com/mongodb/internal/Timeout.java

@@ -23,6 +23,7 @@
 import static com.mongodb.assertions.Assertions.assertFalse;
 import static com.mongodb.assertions.Assertions.assertNotNull;
 import static com.mongodb.assertions.Assertions.assertTrue;
+import static com.mongodb.internal.VisibleForTesting.AccessModifier.PRIVATE;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.concurrent.TimeUnit.NANOSECONDS;
 
@@ -135,13 +136,12 @@ private long elapsedNanos(final long currentNanos) {
     }
 
     /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     * <p>
      * Returns 0 or a positive value.
      * 0 means that the timeout has expired.
      * <p>
      * Must not be called on {@linkplain #isInfinite() infinite} timeouts.
      */
+    @VisibleForTesting(otherwise = PRIVATE)
     long remainingNanos(final long currentNanos) {
         assertFalse(isInfinite() || isImmediate());
         long elapsedNanos = elapsedNanos(currentNanos);
@@ -262,23 +262,17 @@ public String toUserString() {
         }
     }
 
-    /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     */
+    @VisibleForTesting(otherwise = PRIVATE)
     long durationNanos() {
         return durationNanos;
     }
 
-    /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     */
+    @VisibleForTesting(otherwise = PRIVATE)
     long startNanos() {
         return startNanos;
     }
 
-    /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     */
+    @VisibleForTesting(otherwise = PRIVATE)
     static long convertRoundUp(final long nonNegativeNanos, final TimeUnit unit) {
         assertTrue(nonNegativeNanos >= 0);
         if (unit == NANOSECONDS) {

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

@@ -22,6 +22,7 @@
 import com.mongodb.MongoServerUnavailableException;
 import com.mongodb.MongoTimeoutException;
 import com.mongodb.annotations.ThreadSafe;
+import com.mongodb.internal.VisibleForTesting;
 import com.mongodb.internal.connection.ConcurrentLinkedDeque.RemovalReportingIterator;
 import com.mongodb.lang.Nullable;
 
@@ -36,6 +37,7 @@
 import static com.mongodb.assertions.Assertions.assertNotNull;
 import static com.mongodb.assertions.Assertions.assertTrue;
 import static com.mongodb.assertions.Assertions.notNull;
+import static com.mongodb.internal.VisibleForTesting.AccessModifier.PRIVATE;
 
 /**
  * A concurrent pool implementation.
@@ -240,10 +242,9 @@ private T createNewAndReleasePermitIfFailure() {
     }
 
     /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     *
      * @param timeout See {@link com.mongodb.internal.Timeout#startNow(long, TimeUnit)}.
      */
+    @VisibleForTesting(otherwise = PRIVATE)
     boolean acquirePermit(final long timeout, final TimeUnit timeUnit) {
         return stateAndPermits.acquirePermitFair(timeout, timeUnit);
     }

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

@@ -45,6 +45,7 @@
 import com.mongodb.event.ConnectionPoolReadyEvent;
 import com.mongodb.event.ConnectionReadyEvent;
 import com.mongodb.internal.Timeout;
+import com.mongodb.internal.VisibleForTesting;
 import com.mongodb.internal.async.SingleResultCallback;
 import com.mongodb.internal.connection.ConcurrentPool.Prune;
 import com.mongodb.internal.connection.SdamServerDescriptionManager.SdamIssue;
@@ -89,6 +90,7 @@
 import static com.mongodb.assertions.Assertions.fail;
 import static com.mongodb.assertions.Assertions.isTrue;
 import static com.mongodb.assertions.Assertions.notNull;
+import static com.mongodb.internal.VisibleForTesting.AccessModifier.PRIVATE;
 import static com.mongodb.internal.async.ErrorHandlingResultCallback.errorHandlingCallback;
 import static com.mongodb.internal.connection.ConcurrentPool.INFINITE_SIZE;
 import static com.mongodb.internal.connection.ConcurrentPool.sizeToString;
@@ -366,18 +368,15 @@ private MongoTimeoutException createTimeoutException(final Timeout timeout) {
         }
     }
 
-    /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     */
+    @VisibleForTesting(otherwise = PRIVATE)
     ConcurrentPool<UsageTrackingInternalConnection> getPool() {
         return pool;
     }
 
     /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     * <p>
      * Synchronously prune idle connections and ensure the minimum pool size.
      */
+    @VisibleForTesting(otherwise = PRIVATE)
     void doMaintenance() {
         Predicate<RuntimeException> silentlyComplete = e ->
                 e instanceof MongoInterruptedException || e instanceof MongoTimeoutException

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

@@ -33,6 +33,7 @@
 import com.mongodb.event.ServerClosedEvent;
 import com.mongodb.event.ServerListener;
 import com.mongodb.event.ServerOpeningEvent;
+import com.mongodb.internal.VisibleForTesting;
 import com.mongodb.internal.async.SingleResultCallback;
 import com.mongodb.internal.bulk.DeleteRequest;
 import com.mongodb.internal.bulk.InsertRequest;
@@ -50,6 +51,7 @@
 import static com.mongodb.assertions.Assertions.assertNotNull;
 import static com.mongodb.assertions.Assertions.assertTrue;
 import static com.mongodb.assertions.Assertions.notNull;
+import static com.mongodb.internal.VisibleForTesting.AccessModifier.PRIVATE;
 import static com.mongodb.internal.async.ErrorHandlingResultCallback.errorHandlingCallback;
 import static com.mongodb.internal.connection.ServerDescriptionHelper.unknownConnectingServerDescription;
 
@@ -184,23 +186,17 @@ public void connect() {
         serverMonitor.connect();
     }
 
-    /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     */
+    @VisibleForTesting(otherwise = PRIVATE)
     ConnectionPool getConnectionPool() {
         return connectionPool;
     }
 
-    /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     */
+    @VisibleForTesting(otherwise = PRIVATE)
     SdamServerDescriptionManager sdamServerDescriptionManager() {
         return sdam;
     }
 
-    /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     */
+    @VisibleForTesting(otherwise = PRIVATE)
     ServerId serverId() {
         return serverId;
     }

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

@@ -34,6 +34,7 @@
 import com.mongodb.event.ServerDescriptionChangedEvent;
 import com.mongodb.event.ServerListener;
 import com.mongodb.event.ServerOpeningEvent;
+import com.mongodb.internal.VisibleForTesting;
 import com.mongodb.internal.async.SingleResultCallback;
 import com.mongodb.internal.session.SessionContext;
 import org.bson.types.ObjectId;
@@ -42,6 +43,7 @@
 
 import static com.mongodb.assertions.Assertions.isTrue;
 import static com.mongodb.connection.ServerConnectionState.CONNECTING;
+import static com.mongodb.internal.VisibleForTesting.AccessModifier.PRIVATE;
 import static com.mongodb.internal.async.ErrorHandlingResultCallback.errorHandlingCallback;
 
 @ThreadSafe
@@ -143,9 +145,7 @@ public int operationCount() {
         return -1;
     }
 
-    /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     */
+    @VisibleForTesting(otherwise = PRIVATE)
     ConnectionPool getConnectionPool() {
         return connectionPool;
     }

driver-core/src/main/com/mongodb/internal/operation/CommandOperationHelper.java

@@ -29,6 +29,7 @@
 import com.mongodb.assertions.Assertions;
 import com.mongodb.connection.ConnectionDescription;
 import com.mongodb.connection.ServerDescription;
+import com.mongodb.internal.VisibleForTesting;
 import com.mongodb.internal.async.SingleResultCallback;
 import com.mongodb.internal.async.function.AsyncCallbackSupplier;
 import com.mongodb.internal.async.function.RetryState;
@@ -57,6 +58,7 @@
 import static com.mongodb.ReadPreference.primary;
 import static com.mongodb.assertions.Assertions.assertFalse;
 import static com.mongodb.assertions.Assertions.notNull;
+import static com.mongodb.internal.VisibleForTesting.AccessModifier.PRIVATE;
 import static com.mongodb.internal.async.ErrorHandlingResultCallback.errorHandlingCallback;
 import static com.mongodb.internal.operation.OperationHelper.LOGGER;
 import static com.mongodb.internal.operation.OperationHelper.canRetryRead;
@@ -231,9 +233,7 @@ static <D, T> T createReadCommandAndExecute(
 
     /* Write Binding Helpers */
 
-    /**
-     * Is package-access for the purpose of testing and must not be used for any other purpose outside of this class.
-     */
+    @VisibleForTesting(otherwise = PRIVATE)
     static <D, T> T executeCommand(final WriteBinding binding, final String database, final BsonDocument command,
                                    final Decoder<D> decoder, final CommandWriteTransformer<D, T> transformer) {
         return withSourceAndConnection(binding::getWriteConnectionSource, false, (source, connection) ->