--- /dev/null
+++ libmalloc/libmalloc-283.100.6/tests/malloc_free_test.c
@@ -0,0 +1,74 @@
+//
+//  malloc_free_test.c
+//  libmalloc
+//
+//  test allocating and freeing all sizes
+//
+
+#include <darwintest.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <malloc/malloc.h>
+
+T_GLOBAL_META(T_META_RUN_CONCURRENTLY(true));
+
+static inline void*
+t_malloc(size_t s)
+{
+	void *ptr = malloc(s);
+	T_QUIET; T_ASSERT_NOTNULL(ptr, "allocation");
+	size_t sz = malloc_size(ptr);
+	T_QUIET; T_EXPECT_LE(s, sz, "allocation size");
+	const uint64_t pat = 0xdeadbeefcafebabeull;
+	memset_pattern8(ptr, &pat, s);
+	return ptr;
+}
+
+static void
+test_malloc_free(size_t min, size_t max, size_t incr)
+{
+	for (size_t s =  min; s <= max; s += incr) {
+		void *ptr = t_malloc(s);
+		free(ptr); // try to go through mag_last_free SMALL_CACHE
+	}
+	for (size_t s = min, t = max; s <= max; s += incr, t -= incr) {
+		void *ptr1 = t_malloc(s);
+		void *ptr2 = t_malloc(t);
+		free(ptr1); // try to defeat mag_last_free SMALL_CACHE
+		free(ptr2);
+	}
+}
+
+static void
+test_malloc_free_random(size_t min, size_t max, size_t incr, size_t n)
+{
+	const size_t r = (max - min) / incr, P = 100;
+	void *ptrs[P] = {};
+	for (size_t i = 0, j = 0, k = 0; i < n + P; i++, j = k, k = (k + 1) % P) {
+		void *ptr = NULL;
+		if (i < n) ptr = t_malloc(min + arc4random_uniform(r) * incr);
+		free(ptrs[j]);
+		ptrs[k] = ptr;
+	}
+}
+
+T_DECL(malloc_free_nano, "nanomalloc and free all sizes <= 256",
+	   T_META_ENVVAR("MallocNanoZone=1"))
+{
+	test_malloc_free(0, 256, 1); // NANO_MAX_SIZE
+	test_malloc_free_random(0, 256, 1, 10000);
+}
+
+T_DECL(malloc_free_tiny, "tiny malloc and free 16b increments <= 1008",
+	   T_META_ENVVAR("MallocNanoZone=0"))
+{
+	test_malloc_free(0, 1008, 16); // SMALL_THRESHOLD
+	test_malloc_free_random(0, 1008, 16, 10000);
+}
+
+T_DECL(malloc_free, "malloc and free all 512b increments <= 256kb",
+	   T_META_ENVVAR("MallocNanoZone=0"))
+{
+	test_malloc_free(1024, 256 * 1024, 512); // > LARGE_THRESHOLD_LARGEMEM
+	test_malloc_free_random(1024, 256 * 1024, 512, 100000);
+}