PHPLIB-69: Do not allow empty index name for dropIndex()

src/Collection.php

@@ -401,13 +401,16 @@ class Collection
      * @see http://docs.mongodb.org/manual/reference/method/db.collection.dropIndex/
      * @param string $indexName
      * @return Cursor
-     * @throws InvalidArgumentException if "*" is specified, since dropIndexes()
-     *                                  should be used to drop multiple indexes
+     * @throws InvalidArgumentException if $indexName is an empty string or "*"
      */
     public function dropIndex($indexName)
     {
         $indexName = (string) $indexName;
 
+        if ($indexName === '') {
+            throw new InvalidArgumentException('Index name cannot be empty');
+        }
+
         if ($indexName === '*') {
             throw new InvalidArgumentException('dropIndexes() must be used to drop multiple indexes');
         }

tests/CollectionFunctionalTest.php

@@ -150,6 +150,16 @@ class CollectionFunctionalTest extends FunctionalTestCase
         }
     }
 
+    /**
+     * @expectedException MongoDB\Exception\InvalidArgumentException
+     */
+    public function testDropIndexShouldNotAllowEmptyIndexName()
+    {
+        $this->assertSame('x_1', $this->collection->createIndex(array('x' => 1)));
+        $this->assertIndexExists('x_1');
+        $this->collection->dropIndex('');
+    }
+
     /**
      * @expectedException MongoDB\Exception\InvalidArgumentException
      */