From 99233776e61ec03e0ddded469e49559508ca0107 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Tue, 7 Nov 2023 11:14:55 -0500
Subject: [PATCH] test-js: Add a test helper to override the current time zone

---
 Tests/LibJS/test-js.cpp | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/Tests/LibJS/test-js.cpp b/Tests/LibJS/test-js.cpp
index a921778a792..86174d778bf 100644
--- a/Tests/LibJS/test-js.cpp
+++ b/Tests/LibJS/test-js.cpp
@@ -5,8 +5,11 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibCore/System.h>
 #include <LibJS/Runtime/ArrayBuffer.h>
 #include <LibTest/JavaScriptTestRunner.h>
+#include <stdlib.h>
+#include <time.h>
 
 TEST_ROOT("Userland/Libraries/LibJS/Tests");
 
@@ -88,6 +91,26 @@ TESTJS_GLOBAL_FUNCTION(detach_array_buffer, detachArrayBuffer)
     return JS::js_null();
 }
 
+TESTJS_GLOBAL_FUNCTION(set_time_zone, setTimeZone)
+{
+    auto current_time_zone = JS::js_null();
+
+    if (auto const* time_zone = getenv("TZ"))
+        current_time_zone = JS::PrimitiveString::create(vm, StringView { time_zone, strlen(time_zone) });
+
+    if (auto time_zone = vm.argument(0); time_zone.is_null()) {
+        if (auto result = Core::System::unsetenv("TZ"sv); result.is_error())
+            return vm.throw_completion<JS::InternalError>(MUST(String::formatted("Could not unset time zone: {}", result.error())));
+    } else {
+        if (auto result = Core::System::setenv("TZ"sv, TRY(time_zone.to_string(vm)), true); result.is_error())
+            return vm.throw_completion<JS::InternalError>(MUST(String::formatted("Could not set time zone: {}", result.error())));
+    }
+
+    tzset();
+
+    return current_time_zone;
+}
+
 TESTJS_RUN_FILE_FUNCTION(DeprecatedString const& test_file, JS::Realm& realm, JS::ExecutionContext&)
 {
     if (!test262_parser_tests)