--- /dev/null
+++ libmalloc/libmalloc-374.120.1/tests/zone_names.c
@@ -0,0 +1,126 @@
+//
+//  zone_names.c
+//  libmalloc
+//
+//  Documents default zone names and tests malloc_set_zone_name().
+//
+
+#include <darwintest.h>
+
+#include <malloc/malloc.h>
+#include <stdlib.h>  // free()
+
+#include "../src/platform.h"  // CONFIG_NANOZONE
+
+T_GLOBAL_META(T_META_RUN_CONCURRENTLY(true));
+
+static void
+check_zone_names(malloc_zone_t **zones, const char **names, uint32_t count)
+{
+	for (uint32_t i = 0; i < count; i++) {
+		const char *zone_name = malloc_get_zone_name(zones[i]);
+		T_EXPECT_NOTNULL(zone_name, "zone name not null");
+		T_EXPECT_EQ_STR(zone_name, names[i], "zone name %u", i);
+	}
+}
+
+extern int32_t malloc_num_zones;
+extern malloc_zone_t **malloc_zones;
+static void
+check_default_zone_names(const char **names, uint32_t count) {
+	T_EXPECT_EQ(malloc_num_zones, count, "zone count");
+	check_zone_names(malloc_zones, names, count);
+}
+
+T_DECL(default_zone, "Zone names: default",
+		T_META_ENVVAR("MallocNanoZone=0"))
+{
+	const char *names[] = {"DefaultMallocZone"};
+	check_default_zone_names(names, 1);
+}
+
+T_DECL(default_zone_and_nano, "Zone names: default + nano",
+		T_META_ENVVAR("MallocNanoZone=1"))
+{
+#if CONFIG_NANOZONE
+	const char *names[] = {"DefaultMallocZone", "MallocHelperZone"};
+	check_default_zone_names(names, 2);
+#else
+	T_SKIP("Nano allocator not configured");
+#endif
+}
+
+T_DECL(default_zone_and_pgm, "Zone names: default + ProbGuard",
+		T_META_ENVVAR("MallocProbGuard=1"), T_META_ENVVAR("MallocNanoZone=0"))
+{
+	const char *names[] = {"ProbGuardMallocZone", "DefaultMallocZone"};
+	check_default_zone_names(names, 2);
+}
+
+T_DECL(zone_singletons, "Zone singletons")
+{
+	malloc_zone_t *zones[] = {
+		malloc_default_zone(),
+		malloc_default_purgeable_zone()
+	};
+	const char *names[] = {
+		"DefaultMallocZone",
+		"DefaultPurgeableMallocZone"
+	};
+	check_zone_names(zones, names, 2);
+}
+
+static malloc_zone_t *
+call_malloc_zone_from_ptr(void)
+{
+	void *ptr = malloc(5);
+	malloc_zone_t *zone = malloc_zone_from_ptr(ptr);
+	free(ptr);
+	return zone;
+}
+
+T_DECL(virtual_zone0, "Ensure we return the virtual zone in place of zone 0")
+{
+	malloc_zone_t *virtual_zone = malloc_default_zone();
+	T_EXPECT_NE(virtual_zone, malloc_zones[0], NULL);
+	T_EXPECT_EQ(call_malloc_zone_from_ptr(), virtual_zone, NULL);
+}
+
+T_DECL(zone_creation, "Zone creation")
+{
+	T_EXPECT_NULL(malloc_create_zone(0, 0)->zone_name, "No name");
+}
+
+static void
+check_set_zone_name(malloc_zone_t* zone)
+{
+	#define zone_name malloc_get_zone_name(zone)
+
+	char *literal_str = "string literal";
+	malloc_set_zone_name(zone, literal_str);
+	T_EXPECT_EQ(zone_name, literal_str, "skip copy for immutable string");
+
+	char *heap_str = strdup("heap string");
+	malloc_set_zone_name(zone, heap_str);
+	T_EXPECT_NE(zone_name, heap_str, "defensive copy");
+	T_EXPECT_EQ_STR(zone_name, heap_str, "same contents");
+	free(heap_str);
+
+	const char *copy = zone_name;
+	malloc_set_zone_name(zone, NULL);
+	T_EXPECT_NULL(zone_name, "zone name set to NULL");
+	T_EXPECT_EQ(malloc_size(copy), 0ul, "copy freed");
+}
+
+T_DECL(malloc_set_zone_name, "malloc_set_zone_name")
+{
+	malloc_zone_t *zones[] = {
+		malloc_default_zone(),
+		malloc_create_zone(0, 0)
+	};
+
+	size_t count = sizeof(zones) / sizeof(zones[0]);
+	for (uint32_t i = 0; i < count; i++) {
+		check_set_zone_name(zones[i]);
+	}
+}