Test: Add upstream tests

src/tests/test_main.cpp

@@ -7,24 +7,8 @@
 
 /** @file test_main.cpp Entry point for all the unit tests. */
 
-#define OPENTTD_TEST
 #include "../stdafx.h"
 
-#include <stdarg.h>
-#include <stdio.h>
-
 #define CATCH_CONFIG_MAIN
 #define DO_NOT_USE_WMAIN
 #include "../3rdparty/catch2/catch.hpp"
-
-void CDECL error(const char *s, ...)
-{
-	va_list va;
-	char buffer[1024];
-
-	va_start(va, s);
-	vsnprintf(buffer, 1024, s, va);
-	va_end(va);
-
-	CATCH_RUNTIME_ERROR(buffer);
-}