ListCollections functional tests

tests/Operation/ListCollectionsFunctionalTest.php

+<?php
+
+namespace MongoDB\Tests\Operation;
+
+use MongoDB\Driver\Server;
+use MongoDB\Operation\DropDatabase;
+use MongoDB\Operation\ListCollections;
+
+class ListCollectionsFunctionalTest extends FunctionalTestCase
+{
+    public function testListCollectionsForNewlyCreatedDatabase()
+    {
+        $server = $this->getPrimaryServer();
+
+        $operation = new DropDatabase($this->getDatabaseName());
+        $operation->execute($server);
+
+        $writeResult = $this->manager->executeInsert($this->getNamespace(), ['x' => 1]);
+        $this->assertEquals(1, $writeResult->getInsertedCount());
+
+        $operation = new ListCollections($this->getDatabaseName(), ['filter' => ['name' => $this->getCollectionName()]]);
+        // Convert the CollectionInfoIterator to an array since we cannot rewind its cursor
+        $collections = iterator_to_array($operation->execute($server));
+
+        $this->assertCount(1, $collections);
+
+        foreach ($collections as $collection) {
+            $this->assertInstanceOf('MongoDB\Model\CollectionInfo', $collection);
+            $this->assertEquals($this->getCollectionName(), $collection->getName());
+        }
+    }
+
+    public function testListCollectionsForNonexistentDatabase()
+    {
+        $server = $this->getPrimaryServer();
+
+        $operation = new DropDatabase($this->getDatabaseName());
+        $operation->execute($server);
+
+        $operation = new ListCollections($this->getDatabaseName());
+        $collections = $operation->execute($server);
+
+        $this->assertCount(0, $collections);
+    }
+}