[Testing] unbreak after r372963

llvm-svn: 372967
GitOrigin-RevId: 7568899b35cf7d13e523a6a3585d83c727b7091a
diff --git a/test/guard_test_basic.pass.cpp b/test/guard_test_basic.pass.cpp
index a325dd0..7e5b7ac 100644
--- a/test/guard_test_basic.pass.cpp
+++ b/test/guard_test_basic.pass.cpp
@@ -10,6 +10,7 @@
 
 #define TESTING_CXA_GUARD
 #include "../src/cxa_guard_impl.h"
+#include <cassert>
 
 using namespace __cxxabiv1;