samples(spanner): PITR samples backup fix

spanner/src/create_backup.php

@@ -31,24 +31,24 @@
  * Create a backup.
  * Example:
  * ```
- * create_backup($instanceId, $databaseId, $backupId);
+ * create_backup($instanceId, $databaseId, $backupId, $versionTime);
  * ```
  *
  * @param string $instanceId The Spanner instance ID.
  * @param string $databaseId The Spanner database ID.
  * @param string $backupId The Spanner backup ID.
+ * @param string $versionTime The version of the database to backup.
  */
-function create_backup($instanceId, $databaseId, $backupId)
+function create_backup($instanceId, $databaseId, $backupId, $versionTime)
 {
     $spanner = new SpannerClient();
     $instance = $spanner->instance($instanceId);
     $database = $instance->database($databaseId);
 
     $expireTime = new \DateTime('+14 days');
-    $versionTime = new \DateTime($database->info()['earliestVersionTime']);
     $backup = $instance->backup($backupId);
     $operation = $backup->create($database->name(), $expireTime, [
-        'versionTime' => $versionTime
+        'versionTime' => new \DateTime($versionTime)
     ]);
 
     print('Waiting for operation to complete...' . PHP_EOL);

spanner/test/spannerBackupTest.php

@@ -102,9 +102,15 @@ public function testCancelBackup()
      */
     public function testCreateBackup()
     {
+        $database = self::$instance->database(self::$databaseId);
+        $results = $database->execute("SELECT TIMESTAMP_TRUNC(CURRENT_TIMESTAMP(), MICROSECOND) as Timestamp");
+        $row = $results->rows()->current();
+        $versionTime = $row['Timestamp'];
+
         $output = $this->runFunctionSnippet('create_backup', [
             self::$databaseId,
             self::$backupId,
+            $versionTime,
         ]);
         $this->assertStringContainsString(self::$backupId, $output);
     }