PHPC-1875: Session with snapshot=true cannot perform writes

Author: jmikola

tests/session/session-004.phpt

@@ -0,0 +1,34 @@
+--TEST--
+MongoDB\Driver\Session spec test: snapshot option is incompatible with writes
+--DESCRIPTION--
+PHPC-1875: Disable writes on snapshot sessions
+--SKIPIF--
+<?php require __DIR__ . "/../utils/basic-skipif.inc"; ?>
+<?php skip_if_not_libmongoc_crypto(); ?>
+<?php skip_if_not_live(); ?>
+<?php skip_if_server_version('<', '5.0'); ?>
+--FILE--
+<?php
+require_once __DIR__ . "/../utils/basic.inc";
+
+$manager = create_test_manager();
+$session = $manager->startSession(['snapshot' => true]);
+
+$bulk = new MongoDB\Driver\BulkWrite();
+$bulk->insert(['x' => 1]);
+
+try {
+    $manager->executeBulkWrite(NS, $bulk, ['session' => $session]);
+} catch (MongoDB\Driver\Exception\BulkWriteException $e) {
+    /* Note: we intentionally do not assert the server's error message for the
+     * client specifying a read concern on a write command. It is sufficient to
+     * assert that the error code is InvalidOptions(72). */
+    var_dump($e->getCode() === 72);
+}
+
+?>
+===DONE===
+<?php exit(0); ?>
+--EXPECT--
+bool(true)
+===DONE===