LibTest: Support death tests without child process cloning

A challenge for getting LibTest working on Windows has always been CrashTest. It implements death tests similar to Google Test where a child process is cloned to invoke the expression that should abort/terminate the program. Then the exit code of the child is used by the parent test process to verify if the application correctly aborted/terminated due to invoking the expression. The problem was that finding an equivalent way to port Crash::run() to Windows was not looking very likely as publicly exposed Win32/ Native APIs have no equivalent to fork(); however, Windows actually does have native support for process cloning via undocumented NT APIs that clever people reverse engineered and published, see `NtCreateUserProcess()`. All that being said, this `EXPECT_DEATH()` implementation avoids needing to use a child process in general, allowing us to remove CrashTest in favour of a single cross-platform solution for death tests.
Author: https://github.com/ayeteadoe Commit: 744fd91d0b Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4698 Reviewed-by: https://github.com/ADKaster ✅ Reviewed-by: https://github.com/AtkinsSJ Reviewed-by: https://github.com/R-Goc
2025-07-29 20:29:18 +00:00 · 2025-05-15 07:55:33 -07:00 · 2025-05-15 07:55:33 -07:00 · 744fd91d0b · 2025-05-16 19:24:44 +00:00
commit 744fd91d0b
parent dc707e6ed8
13 changed files with 133 additions and 101 deletions
--- a/Libraries/LibTest/AssertionHandler.cpp
+++ b/Libraries/LibTest/AssertionHandler.cpp
@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2025, ayeteadoe <ayeteadoe@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibTest/Macros.h>
+
+namespace Test {
+
+static jmp_buf g_assert_jmp_buf = {};
+
+static bool g_assert_jmp_buf_valid = false;
+
+jmp_buf& assertion_jump_buffer() { return g_assert_jmp_buf; }
+
+void set_assertion_jump_validity(bool validity)
+{
+    g_assert_jmp_buf_valid = validity;
+}
+
+static bool is_assertion_jump_valid()
+{
+    return g_assert_jmp_buf_valid;
+}
+
+static void assertion_handler_impl(char const*)
+{
+    if (is_assertion_jump_valid()) {
+        set_assertion_jump_validity(false);
+        LIBTEST_LONGJMP(assertion_jump_buffer(), 1); /* NOLINT(cert-err52-cpp, bugprone-setjmp-longjmp) Isolated to test infrastructure and allows us to not depend on spawning child processes for death tests */
+    }
+    // Fall through to default assertion handler
+}
+
+}
+
+#if defined(AK_OS_WINDOWS)
+#    define EXPORT __declspec(dllexport)
+#else
+#    define EXPORT __attribute__((visibility("default")))
+#endif
+
+extern "C" EXPORT void ak_assertion_handler(char const* message);
+void ak_assertion_handler(char const* message)
+{
+    ::Test::assertion_handler_impl(message);
+}