Revise spec test for state of change stream cursor

The spec requests that we check that the initial change stream cursor is alive. This can be done by both asserting its cursor ID is non-zero and also calling MongoDB\Driver\Cursor::isDead().

Author: jmikola

tests/Operation/WatchFunctionalTest.php

@@ -13,6 +13,7 @@
 use MongoDB\Operation\Watch;
 use MongoDB\Tests\CommandObserver;
 use stdClass;
+use ReflectionClass;
 
 class WatchFunctionalTest extends FunctionalTestCase
 {
@@ -230,12 +231,31 @@ public function testNonEmptyPipeline()
         $this->assertSameDocument($expectedResult, $changeStream->current());
     }
 
-    public function testCursorWithEmptyBatchNotClosed()
+    public function testInitialCursorIsNotClosed()
     {
-        $operation = new Watch($this->manager, $this->getDatabaseName(), $this->getCollectionName(), [], ['maxAwaitTimeMS' => 100]);
+        $operation = new Watch($this->manager, $this->getDatabaseName(), $this->getCollectionName(), []);
         $changeStream = $operation->execute($this->getPrimaryServer());
 
-        $this->assertNotNull($changeStream);
+        /* The spec requests that we assert that the cursor returned from the
+         * aggregate command is not closed on the driver side. We will verify
+         * this by checking that the cursor ID is non-zero and that libmongoc
+         * reports the cursor as alive. While the cursor ID is easily accessed
+         * through ChangeStream, we'll need to use reflection to access the
+         * internal Cursor and call isDead(). */
+        $this->assertNotEquals('0', (string) $changeStream->getCursorId());
+
+        $rc = new ReflectionClass('MongoDB\ChangeStream');
+        $rp = $rc->getProperty('csIt');
+        $rp->setAccessible(true);
+
+        $iterator = $rp->getValue($changeStream);
+
+        $this->assertInstanceOf('IteratorIterator', $iterator);
+
+        $cursor = $iterator->getInnerIterator();
+
+        $this->assertInstanceOf('MongoDB\Driver\Cursor', $cursor);
+        $this->assertFalse($cursor->isDead());
     }
 
     /**