--- /dev/null
+++ libmalloc/libmalloc-283.60.1/tests/malloc_heap_check_test.c
@@ -0,0 +1,59 @@
+//
+//  malloc_heap_check_test.c
+//  libsystem_malloc
+//
+//  Created by Kim Topley on 4/26/18.
+//
+#include <stdlib.h>
+#include <darwintest.h>
+
+T_GLOBAL_META(T_META_RUN_CONCURRENTLY(true));
+
+static void
+run_heap_test()
+{
+	const int MAX_POINTERS = 1024;
+	void **pointers = (void **)calloc(MAX_POINTERS, sizeof(void *));
+	for (int iteration = 0; iteration < 100000; iteration++) {
+		int index = random() % MAX_POINTERS;
+		size_t size = 1 << (random() % 20);
+		if (pointers[index]) {
+			if (random() % 4 == 0) {
+				pointers[index] = realloc(pointers[index], size);
+				continue;
+			}
+			free(pointers[index]);
+			pointers[index] = NULL;
+		}
+		void * pointer = malloc(size);
+		T_QUIET; T_ASSERT_NOTNULL(pointer, "Allocation failed for %llu\n",
+				(uint64_t)size);
+		pointers[index] = pointer;
+	}
+	for (int i = 0; i < MAX_POINTERS; i++) {
+		free(pointers[i]);
+	}
+	free(pointers);
+}
+
+T_DECL(malloc_heap_check_no_nano, "malloc heap checking (no Nano)",
+	   T_META_ENVVAR("MallocCheckHeapStart=1"),
+	   T_META_ENVVAR("MallocCheckHeapEach=1"),
+	   T_META_ENVVAR("MallocNanoZone=0"))
+{
+	run_heap_test();
+
+	// If we get here without crashing, we pass.
+	T_PASS("Heap check succeeded");
+}
+T_DECL(malloc_heap_check_nano, "malloc heap checking (with Nano)",
+	   T_META_ENVVAR("MallocCheckHeapStart=1"),
+	   T_META_ENVVAR("MallocCheckHeapEach=1"),
+	   T_META_ENVVAR("MallocNanoZone=1"))
+{
+	run_heap_test();
+
+	// If we get here without crashing, we pass.
+	T_PASS("Heap check succeeded");
+}
+