--- /dev/null
+++ libmalloc/libmalloc-521.100.59/tests/xzone_metapool_tests.c
@@ -0,0 +1,97 @@
+#include <darwintest.h>
+#include <mach/mach_init.h>
+#include <mach/vm_map.h>
+#include <sys/mman.h>
+
+#if CONFIG_XZONE_MALLOC
+
+static void *
+test_mvm_allocate_pages(size_t size, int vm_page_label)
+{
+	vm_address_t vm_addr;
+	kern_return_t kr;
+
+	kr = vm_allocate(mach_task_self(), &vm_addr, size,
+			VM_FLAGS_ANYWHERE | VM_MAKE_TAG(vm_page_label));
+	return kr == KERN_SUCCESS ? (void *)vm_addr : NULL;
+}
+#define mvm_allocate_plat(addr, size, align, flags, debug_flags, vm_page_label, plat) \
+	test_mvm_allocate_pages(size, vm_page_label)
+
+
+static int
+test_mvm_madvise(void *addr, size_t size, int advice)
+{
+	kern_return_t kr = madvise(addr, size, advice);
+	return kr != - 1;
+}
+#define mvm_madvise_plat(addr, size, advice, debug_flags, plat) \
+	test_mvm_madvise(addr, size, advice)
+
+#include "../src/xzone/xzone_metapool.c"
+
+bool check_page_is_dirty(void *page) {
+	int disposition = 0;
+	mach_vm_size_t disp_count = 1;
+
+	kern_return_t kr = mach_vm_page_range_query(mach_task_self(),
+			(mach_vm_address_t)page, KiB(16), (mach_vm_address_t)&disposition,
+			&disp_count);
+	T_QUIET; T_ASSERT_EQ(kr, KERN_SUCCESS, "Query page disposition");
+	return disposition & VM_PAGE_QUERY_PAGE_DIRTY;
+}
+
+T_DECL(xzone_metapool_metadata,
+		"Check that metapools with metadata allocator madvise blocks") {
+	struct xzm_metapool_s metadata_pool = { 0 };
+	struct xzm_metapool_s data_pool = { 0 };
+
+	// Constants
+	const size_t metadata_size = MAX(sizeof(struct xzm_metapool_block_s),
+			sizeof(struct xzm_metapool_slab_s));
+	const size_t metadata_slab_size = KiB(16);
+
+	const size_t data_size = KiB(16);
+	const size_t data_slab_size = KiB(512);
+	const size_t num_data_blocks = data_slab_size / data_size;
+
+	xzm_metapool_init(&metadata_pool, 1, metadata_slab_size, metadata_size,
+			metadata_size, NULL);
+	xzm_metapool_init(&data_pool, 1, data_slab_size, data_size,
+			data_size, &metadata_pool);
+
+	// Allocate a full slab of data blocks, ensure that they all came from the
+	// same slab, dirty all of their pages, and then free them all. After
+	// freeing, the pages should be madvised
+	void *data[num_data_blocks];
+	for (int i = 0; i < num_data_blocks; i++) {
+		data[i] = xzm_metapool_alloc(&data_pool);
+		T_ASSERT_NOTNULL(data[i], "Allocate data block");
+		if (i != 0) {
+			T_ASSERT_EQ((uintptr_t)data[i] - (uintptr_t)data[i-1], data_size,
+				"All data blocks are from the same slab");
+		}
+	}
+
+	for (int i = 0; i < num_data_blocks; i++) {
+		memset(data[i], 'A', data_size);
+		T_EXPECT_TRUE(check_page_is_dirty(data[i]),
+				"Page is dirty after memset");
+
+	}
+
+	for (int i = 0; i < num_data_blocks; i++) {
+		xzm_metapool_free(&data_pool, data[i]);
+		T_EXPECT_FALSE(check_page_is_dirty(data[i]),
+				"Freed page is not dirty");
+	}
+}
+
+#else // CONFIG_XZONE_MALLOC
+
+T_DECL(xzm_metapool_not_supported, "xzone metapool not supported")
+{
+	T_SKIP("xzone metapool not supported on this platform");
+}
+
+#endif // CONFIG_XZONE_MALLOC