test: disallow running the test suite as root

The test suite is known to have issues when run as root. This
commit prevents the test suite from running when the euid is 0.

Fixes: #2549
PR-URL: #2585
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

test/run-tests.c

@@ -51,6 +51,13 @@ static int maybe_run_test(int argc, char **argv);
 
 
 int main(int argc, char **argv) {
+#ifndef _WIN32
+  if (0 == geteuid() && NULL == getenv("UV_RUN_AS_ROOT")) {
+    fprintf(stderr, "The libuv test suite cannot be run as root.\n");
+    return EXIT_FAILURE;
+  }
+#endif
+
   if (platform_init(argc, argv))
     return EXIT_FAILURE;