Add a couple of demangler tests.

Bug: http://b/152588929
Test: treehugger
Change-Id: I4528e464f969e9167d459f292b179d14381d0f2e
diff --git a/tests/__cxa_demangle_test.cpp b/tests/__cxa_demangle_test.cpp
new file mode 100644
index 0000000..365d96b
--- /dev/null
+++ b/tests/__cxa_demangle_test.cpp
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <cxxabi.h>
+#include <gtest/gtest.h>
+
+extern "C" char* __cxa_demangle(const char*, char*, size_t*, int*);
+
+TEST(__cxa_demangle, cxa_demangle_fuzz_152588929) {
+#if defined(__aarch64__)
+  char* p = __cxa_demangle("1\006ILeeeEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE", 0, 0, 0);
+  ASSERT_STREQ("\x6<-0x1.cecececececececececececececep+11983", p);
+  free(p);
+#endif
+}
+
+TEST(__cxa_demangle, cxa_demangle_fuzz_167977068) {
+#if defined(__aarch64__)
+  ASSERT_TRUE(__cxa_demangle("DTLeeeeeeeeeeeeeeeeeeeeeeeeeEEEEeeEEEE", 0, 0, 0) == nullptr);
+#endif
+}