PHPLIB-72: Database enumeration method

src/Client.php

@@ -7,6 +7,9 @@ use MongoDB\Driver\Manager;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Result;
 use MongoDB\Driver\WriteConcern;
+use ArrayIterator;
+use stdClass;
+use UnexpectedValueException;
 
 class Client
 {
@@ -47,6 +50,39 @@ class Client
         return $this->manager->executeCommand($databaseName, $command, $readPreference);
     }
 
+    /**
+     * List databases.
+     *
+     * @see http://docs.mongodb.org/manual/reference/command/listDatabases/
+     * @return Traversable
+     * @throws UnexpectedValueException if the command result is malformed
+     */
+    public function listDatabases()
+    {
+        $command = new Command(array('listDatabases' => 1));
+
+        $result = $this->manager->executeCommand('admin', $command);
+        $result = iterator_to_array($result);
+        $result = current($result);
+
+        if ( ! isset($result['databases']) || ! is_array($result['databases'])) {
+            throw new UnexpectedValueException('listDatabases command did not return a "databases" array');
+        }
+
+        $databases = array_map(
+            function(stdClass $database) { return (array) $database; },
+            $result['databases']
+        );
+
+        /* Return a Traversable instead of an array in case listDatabases is
+         * eventually changed to return a command cursor, like the collection
+         * and index enumeration commands. This makes the "totalSize" command
+         * field inaccessible, but users can manually invoke the command if they
+         * need that value.
+         */
+        return new ArrayIterator($databases);
+    }
+
     /**
      * Select a database.
      *

tests/ClientFunctionalTest.php

@@ -19,4 +19,28 @@ class ClientFunctionalTest extends FunctionalTestCase
         $this->assertCommandSucceeded($commandResult);
         $this->assertCollectionCount($this->getNamespace(), 0);
     }
+
+    public function testListDatabases()
+    {
+        $writeResult = $this->manager->executeInsert($this->getNamespace(), array('x' => 1));
+        $this->assertEquals(1, $writeResult->getInsertedCount());
+
+        $client = new Client($this->getUri());
+        $databases = $client->listDatabases();
+
+        $this->assertInstanceOf('Traversable', $databases);
+
+        $foundDatabase = null;
+
+        foreach ($databases as $database) {
+            if ($database['name'] === $this->getDatabaseName()) {
+                $foundDatabase = $database;
+                break;
+            }
+        }
+
+        $this->assertNotNull($foundDatabase, 'Found test database in list of databases');
+        $this->assertFalse($foundDatabase['empty'], 'Test database is not empty');
+        $this->assertGreaterThan(0, $foundDatabase['sizeOnDisk'], 'Test database takes up disk space');
+    }
 }