Safetensor support (#215)

Co-authored-by: Awni Hannun <awni@apple.com>

.gitignore

@@ -6,6 +6,10 @@ __pycache__/
 # C extensions
 *.so
 
+# tensor files
+*.safe
+*.safetensors
+
 # Metal libraries
 *.metallib
 venv/

CMakeLists.txt

@@ -98,6 +98,15 @@ elseif (MLX_BUILD_METAL)
     ${QUARTZ_LIB})
 endif()
 
+MESSAGE(STATUS "Downloading json")
+FetchContent_Declare(json URL https://github.com/nlohmann/json/releases/download/v3.11.3/json.tar.xz)
+FetchContent_MakeAvailable(json)
+target_include_directories(
+    mlx PUBLIC
+    $<BUILD_INTERFACE:${json_SOURCE_DIR}/single_include/nlohmann>
+    $<INSTALL_INTERFACE:include/json>
+)
+
 find_library(ACCELERATE_LIBRARY Accelerate)
 if (MLX_BUILD_ARM AND ACCELERATE_LIBRARY)
   message(STATUS "Accelerate found ${ACCELERATE_LIBRARY}")
@@ -152,6 +161,8 @@ if (MLX_BUILD_BENCHMARKS)
   add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/benchmarks/cpp)
 endif()
 
+
+
 # ----------------------------- Installation -----------------------------
 include(GNUInstallDirs)
 

docs/src/python/ops.rst

@@ -83,6 +83,7 @@ Operations
    save
    savez
    savez_compressed
+   save_safetensors
    sigmoid
    sign
    sin

mlx/CMakeLists.txt

@@ -8,7 +8,6 @@ target_sources(
   ${CMAKE_CURRENT_SOURCE_DIR}/fft.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/ops.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/graph_utils.cpp
-  ${CMAKE_CURRENT_SOURCE_DIR}/load.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/primitives.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/random.cpp
   ${CMAKE_CURRENT_SOURCE_DIR}/scheduler.cpp
@@ -19,7 +18,7 @@ target_sources(
 )
 
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/backend/common)
-
+add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/io)
 if (MLX_BUILD_ACCELERATE) 
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/backend/accelerate)
 else()

mlx/backend/common/load.cpp

@@ -5,7 +5,7 @@
 #include <utility>
 
 #include "mlx/allocator.h"
-#include "mlx/load.h"
+#include "mlx/io/load.h"
 #include "mlx/primitives.h"
 
 namespace mlx::core {

mlx/io/CMakeLists.txt

@@ -0,0 +1,6 @@
+target_sources(
+  mlx
+  PRIVATE
+  ${CMAKE_CURRENT_SOURCE_DIR}/load.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/safetensor.cpp
+)

mlx/io/load.cpp

@@ -6,7 +6,7 @@
 #include <limits>
 #include <sstream>
 
-#include "mlx/load.h"
+#include "mlx/io/load.h"
 #include "mlx/ops.h"
 #include "mlx/primitives.h"
 #include "mlx/utils.h"

mlx/io/safetensor.cpp

@@ -0,0 +1,189 @@
+#include "mlx/io/safetensor.h"
+
+#include <stack>
+
+namespace mlx::core {
+
+std::string dtype_to_safetensor_str(Dtype t) {
+  switch (t) {
+    case float32:
+      return ST_F32;
+    case bfloat16:
+      return ST_BF16;
+    case float16:
+      return ST_F16;
+    case int64:
+      return ST_I64;
+    case int32:
+      return ST_I32;
+    case int16:
+      return ST_I16;
+    case int8:
+      return ST_I8;
+    case uint64:
+      return ST_U64;
+    case uint32:
+      return ST_U32;
+    case uint16:
+      return ST_U16;
+    case uint8:
+      return ST_U8;
+    case bool_:
+      return ST_BOOL;
+    case complex64:
+      return ST_C64;
+  }
+}
+
+Dtype dtype_from_safetensor_str(std::string str) {
+  if (str == ST_F32) {
+    return float32;
+  } else if (str == ST_F16) {
+    return float16;
+  } else if (str == ST_BF16) {
+    return bfloat16;
+  } else if (str == ST_I64) {
+    return int64;
+  } else if (str == ST_I32) {
+    return int32;
+  } else if (str == ST_I16) {
+    return int16;
+  } else if (str == ST_I8) {
+    return int8;
+  } else if (str == ST_U64) {
+    return uint64;
+  } else if (str == ST_U32) {
+    return uint32;
+  } else if (str == ST_U16) {
+    return uint16;
+  } else if (str == ST_U8) {
+    return uint8;
+  } else if (str == ST_BOOL) {
+    return bool_;
+  } else if (str == ST_C64) {
+    return complex64;
+  } else {
+    throw std::runtime_error("[safetensor] unsupported dtype " + str);
+  }
+}
+
+/** Load array from reader in safetensor format */
+std::unordered_map<std::string, array> load_safetensors(
+    std::shared_ptr<io::Reader> in_stream,
+    StreamOrDevice s) {
+  ////////////////////////////////////////////////////////
+  // Open and check file
+  if (!in_stream->good() || !in_stream->is_open()) {
+    throw std::runtime_error(
+        "[load_safetensors] Failed to open " + in_stream->label());
+  }
+
+  uint64_t jsonHeaderLength = 0;
+  in_stream->read(reinterpret_cast<char*>(&jsonHeaderLength), 8);
+  if (jsonHeaderLength <= 0) {
+    throw std::runtime_error(
+        "[load_safetensors] Invalid json header length " + in_stream->label());
+  }
+  // Load the json metadata
+  char rawJson[jsonHeaderLength];
+  in_stream->read(rawJson, jsonHeaderLength);
+  auto metadata = json::parse(rawJson, rawJson + jsonHeaderLength);
+  // Should always be an object on the top-level
+  if (!metadata.is_object()) {
+    throw std::runtime_error(
+        "[load_safetensors] Invalid json metadata " + in_stream->label());
+  }
+  size_t offset = jsonHeaderLength + 8;
+  // Load the arrays using metadata
+  std::unordered_map<std::string, array> res;
+  for (const auto& item : metadata.items()) {
+    if (item.key() == "__metadata__") {
+      // ignore metadata for now
+      continue;
+    }
+    std::string dtype = item.value().at("dtype");
+    std::vector<int> shape = item.value().at("shape");
+    std::vector<size_t> data_offsets = item.value().at("data_offsets");
+    Dtype type = dtype_from_safetensor_str(dtype);
+    auto loaded_array = array(
+        shape,
+        type,
+        std::make_unique<Load>(
+            to_stream(s), in_stream, offset + data_offsets.at(0), false),
+        std::vector<array>{});
+    res.insert({item.key(), loaded_array});
+  }
+  return res;
+}
+
+std::unordered_map<std::string, array> load_safetensors(
+    const std::string& file,
+    StreamOrDevice s) {
+  return load_safetensors(std::make_shared<io::FileReader>(file), s);
+}
+
+/** Save array to out stream in .npy format */
+void save_safetensors(
+    std::shared_ptr<io::Writer> out_stream,
+    std::unordered_map<std::string, array> a,
+    std::optional<bool> retain_graph_) {
+  ////////////////////////////////////////////////////////
+  // Check file
+  if (!out_stream->good() || !out_stream->is_open()) {
+    throw std::runtime_error(
+        "[save_safetensors] Failed to open " + out_stream->label());
+  }
+
+  ////////////////////////////////////////////////////////
+  // Check array map
+  json parent;
+  parent["__metadata__"] = json::object({
+      {"format", "mlx"},
+  });
+  size_t offset = 0;
+  for (auto& [key, arr] : a) {
+    arr.eval(retain_graph_.value_or(arr.is_tracer()));
+    if (arr.nbytes() == 0) {
+      throw std::invalid_argument(
+          "[save_safetensors] cannot serialize an empty array key: " + key);
+    }
+
+    if (!arr.flags().contiguous) {
+      throw std::invalid_argument(
+          "[save_safetensors] cannot serialize a non-contiguous array key: " +
+          key);
+    }
+    json child;
+    child["dtype"] = dtype_to_safetensor_str(arr.dtype());
+    child["shape"] = arr.shape();
+    child["data_offsets"] = std::vector<size_t>{offset, offset + arr.nbytes()};
+    parent[key] = child;
+    offset += arr.nbytes();
+  }
+
+  auto header = parent.dump();
+  uint64_t header_len = header.length();
+  out_stream->write(reinterpret_cast<char*>(&header_len), 8);
+  out_stream->write(header.c_str(), header_len);
+  for (auto& [key, arr] : a) {
+    out_stream->write(arr.data<char>(), arr.nbytes());
+  }
+}
+
+void save_safetensors(
+    const std::string& file_,
+    std::unordered_map<std::string, array> a,
+    std::optional<bool> retain_graph) {
+  // Open and check file
+  std::string file = file_;
+
+  // Add .safetensors to file name if it is not there
+  if (file.length() < 12 ||
+      file.substr(file.length() - 12, 12) != ".safetensors")
+    file += ".safetensors";
+
+  // Serialize array
+  save_safetensors(std::make_shared<io::FileWriter>(file), a, retain_graph);
+}
+
+} // namespace mlx::core

mlx/io/safetensor.h

@@ -0,0 +1,32 @@
+// Copyright © 2023 Apple Inc.
+
+#pragma once
+
+#include <json.hpp>
+
+#include "mlx/io/load.h"
+#include "mlx/ops.h"
+#include "mlx/primitives.h"
+
+using json = nlohmann::json;
+
+namespace mlx::core {
+
+#define ST_F16 "F16"
+#define ST_BF16 "BF16"
+#define ST_F32 "F32"
+
+#define ST_BOOL "BOOL"
+#define ST_I8 "I8"
+#define ST_I16 "I16"
+#define ST_I32 "I32"
+#define ST_I64 "I64"
+#define ST_U8 "U8"
+#define ST_U16 "U16"
+#define ST_U32 "U32"
+#define ST_U64 "U64"
+
+// Note: Complex numbers aren't in the spec yet so this could change -
+// https://github.com/huggingface/safetensors/issues/389
+#define ST_C64 "C64"
+} // namespace mlx::core

mlx/ops.h

@@ -7,7 +7,7 @@
 
 #include "array.h"
 #include "device.h"
-#include "load.h"
+#include "io/load.h"
 #include "stream.h"
 
 namespace mlx::core {
@@ -1057,4 +1057,20 @@ array dequantize(
     int bits = 4,
     StreamOrDevice s = {});
 
+/** Load array map from .safetensors file format */
+std::unordered_map<std::string, array> load_safetensors(
+    std::shared_ptr<io::Reader> in_stream,
+    StreamOrDevice s = {});
+std::unordered_map<std::string, array> load_safetensors(
+    const std::string& file,
+    StreamOrDevice s = {});
+
+void save_safetensors(
+    std::shared_ptr<io::Writer> in_stream,
+    std::unordered_map<std::string, array>,
+    std::optional<bool> retain_graph = std::nullopt);
+void save_safetensors(
+    const std::string& file,
+    std::unordered_map<std::string, array>,
+    std::optional<bool> retain_graph = std::nullopt);
 } // namespace mlx::core

mlx/primitives.h

@@ -4,7 +4,7 @@
 
 #include "array.h"
 #include "device.h"
-#include "load.h"
+#include "io/load.h"
 #include "stream.h"
 
 #define DEFINE_GRADS()                           \

python/src/load.cpp

@@ -6,12 +6,11 @@
 #include <cstring>
 #include <fstream>
 #include <stdexcept>
-#include <string>
 #include <string_view>
 #include <unordered_map>
 #include <vector>
 
-#include "mlx/load.h"
+#include "mlx/io/load.h"
 #include "mlx/ops.h"
 #include "mlx/utils.h"
 #include "python/src/load.h"
@@ -161,40 +160,68 @@ class PyFileReader : public io::Reader {
   py::object tell_func_;
 };
 
-DictOrArray mlx_load_helper(py::object file, StreamOrDevice s) {
-  py::module_ zipfile = py::module_::import("zipfile");
-
-  // Assume .npz file if it is zipped
-  if (is_zip_file(zipfile, file)) {
-    // Output dictionary filename in zip -> loaded array
-    std::unordered_map<std::string, array> array_dict;
-
-    // Create python ZipFile object
-    ZipFileWrapper zipfile_object(zipfile, file);
-    for (const std::string& st : zipfile_object.namelist()) {
-      // Open zip file as a python file stream
-      py::object sub_file = zipfile_object.open(st);
-
-      // Create array from python fille stream
-      auto arr = load(std::make_shared<PyFileReader>(sub_file), s);
-
-      // Remove .npy from file if it is there
-      auto key = st;
-      if (st.length() > 4 && st.substr(st.length() - 4, 4) == ".npy")
-        key = st.substr(0, st.length() - 4);
-
-      // Add array to dict
-      array_dict.insert({key, arr});
-    }
-
+std::unordered_map<std::string, array> mlx_load_safetensor_helper(
+    py::object file,
+    StreamOrDevice s) {
+  if (py::isinstance<py::str>(file)) { // Assume .safetensors file path string
+    return {load_safetensors(py::cast<std::string>(file), s)};
+  } else if (is_istream_object(file)) {
     // If we don't own the stream and it was passed to us, eval immediately
-    for (auto& [key, arr] : array_dict) {
+    auto arr = load_safetensors(std::make_shared<PyFileReader>(file), s);
+    {
       py::gil_scoped_release gil;
-      arr.eval();
+      for (auto& [key, arr] : arr) {
+        arr.eval();
+      }
     }
+    return {arr};
+  }
 
-    return {array_dict};
-  } else if (py::isinstance<py::str>(file)) { // Assume .npy file path string
+  throw std::invalid_argument(
+      "[load_safetensors] Input must be a file-like object, or string");
+}
+
+std::unordered_map<std::string, array> mlx_load_npz_helper(
+    py::object file,
+    StreamOrDevice s) {
+  py::module_ zipfile = py::module_::import("zipfile");
+  if (!is_zip_file(zipfile, file)) {
+    throw std::invalid_argument(
+        "[load_npz] Input must be a zip file or a file-like object that can be "
+        "opened with zipfile.ZipFile");
+  }
+  // Output dictionary filename in zip -> loaded array
+  std::unordered_map<std::string, array> array_dict;
+
+  // Create python ZipFile object
+  ZipFileWrapper zipfile_object(zipfile, file);
+  for (const std::string& st : zipfile_object.namelist()) {
+    // Open zip file as a python file stream
+    py::object sub_file = zipfile_object.open(st);
+
+    // Create array from python fille stream
+    auto arr = load(std::make_shared<PyFileReader>(sub_file), s);
+
+    // Remove .npy from file if it is there
+    auto key = st;
+    if (st.length() > 4 && st.substr(st.length() - 4, 4) == ".npy")
+      key = st.substr(0, st.length() - 4);
+
+    // Add array to dict
+    array_dict.insert({key, arr});
+  }
+
+  // If we don't own the stream and it was passed to us, eval immediately
+  for (auto& [key, arr] : array_dict) {
+    py::gil_scoped_release gil;
+    arr.eval();
+  }
+
+  return {array_dict};
+}
+
+array mlx_load_npy_helper(py::object file, StreamOrDevice s) {
+  if (py::isinstance<py::str>(file)) { // Assume .npy file path string
     return {load(py::cast<std::string>(file), s)};
   } else if (is_istream_object(file)) {
     // If we don't own the stream and it was passed to us, eval immediately
@@ -205,9 +232,41 @@ DictOrArray mlx_load_helper(py::object file, StreamOrDevice s) {
     }
     return {arr};
   }
-
   throw std::invalid_argument(
-      "[load] Input must be a file-like object, string, or pathlib.Path");
+      "[load_npy] Input must be a file-like object, or string");
+}
+
+DictOrArray mlx_load_helper(
+    py::object file,
+    std::optional<std::string> format,
+    StreamOrDevice s) {
+  if (!format.has_value()) {
+    std::string fname;
+    if (py::isinstance<py::str>(file)) {
+      fname = py::cast<std::string>(file);
+    } else if (is_istream_object(file)) {
+      fname = file.attr("name").cast<std::string>();
+    } else {
+      throw std::invalid_argument(
+          "[load] Input must be a file-like object, or string");
+    }
+    size_t ext = fname.find_last_of('.');
+    if (ext == std::string::npos) {
+      throw std::invalid_argument(
+          "[load] Could not infer file format from extension");
+    }
+    format.emplace(fname.substr(ext + 1));
+  }
+
+  if (format.value() == "safetensors") {
+    return mlx_load_safetensor_helper(file, s);
+  } else if (format.value() == "npz") {
+    return mlx_load_npz_helper(file, s);
+  } else if (format.value() == "npy") {
+    return mlx_load_npy_helper(file, s);
+  } else {
+    throw std::invalid_argument("[load] Unknown file format " + format.value());
+  }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -305,7 +364,7 @@ void mlx_save_helper(
   }
 
   throw std::invalid_argument(
-      "[save] Input must be a file-like object, string, or pathlib.Path");
+      "[save] Input must be a file-like object, or string");
 }
 
 void mlx_savez_helper(
@@ -361,3 +420,25 @@ void mlx_savez_helper(
 
   return;
 }
+
+void mlx_save_safetensor_helper(
+    py::object file,
+    py::dict d,
+    std::optional<bool> retain_graph) {
+  auto arrays_map = d.cast<std::unordered_map<std::string, array>>();
+  if (py::isinstance<py::str>(file)) {
+    save_safetensors(py::cast<std::string>(file), arrays_map, retain_graph);
+    return;
+  } else if (is_ostream_object(file)) {
+    auto writer = std::make_shared<PyFileWriter>(file);
+    {
+      py::gil_scoped_release gil;
+      save_safetensors(writer, arrays_map, retain_graph);
+    }
+
+    return;
+  }
+
+  throw std::invalid_argument(
+      "[save_safetensors] Input must be a file-like object, or string");
+}

python/src/load.h

@@ -3,6 +3,8 @@
 #pragma once
 
 #include <pybind11/pybind11.h>
+#include <optional>
+#include <string>
 #include <unordered_map>
 #include <variant>
 #include "mlx/ops.h"
@@ -12,7 +14,18 @@ using namespace mlx::core;
 
 using DictOrArray = std::variant<array, std::unordered_map<std::string, array>>;
 
-DictOrArray mlx_load_helper(py::object file, StreamOrDevice s);
+std::unordered_map<std::string, array> mlx_load_safetensor_helper(
+    py::object file,
+    StreamOrDevice s);
+void mlx_save_safetensor_helper(
+    py::object file,
+    py::dict d,
+    std::optional<bool> retain_graph = std::nullopt);
+
+DictOrArray mlx_load_helper(
+    py::object file,
+    std::optional<std::string> format,
+    StreamOrDevice s);
 void mlx_save_helper(
     py::object file,
     array a,

python/src/ops.cpp

@@ -2867,11 +2867,9 @@ void init_ops(py::module_& m) {
         Args:
             file (str): File to which the array is saved
             arr (array): Array to be saved.
-            retain_graph (bool, optional): Optional argument to retain graph
-              during array evaluation before saving. If not provided the graph
-              is retained if we are during a function transformation. Default:
-              None
-
+            retain_graph (bool, optional): Whether or not to retain the graph
+              during array evaluation. If left unspecified the graph is retained
+              only if saving is done in a function transformation. Default: ``None``
       )pbdoc");
   m.def(
       "savez",
@@ -2932,18 +2930,45 @@ void init_ops(py::module_& m) {
       &mlx_load_helper,
       "file"_a,
       py::pos_only(),
+      "format"_a = none,
       py::kw_only(),
       "stream"_a = none,
       R"pbdoc(
-        load(file: str, /, *, stream: Union[None, Stream, Device] = None) -> Union[array, Dict[str, array]]
+        load(file: str, /, format: Optional[str] = None, *, stream: Union[None, Stream, Device] = None) -> Union[array, Dict[str, array]]
 
-        Load array(s) from a binary file in ``.npy`` or ``.npz`` format.
+        Load array(s) from a binary file in ``.npy``, ``.npz``, or ``.safetensors`` format.
 
         Args:
-            file (file, str): File in which the array is saved
-
+            file (file, str): File in which the array is saved.
+            format (str, optional): Format of the file. If ``None``, the format
+              is inferred from the file extension. Supported formats: ``npy``,
+              ``npz``, and ``safetensors``. Default: ``None``.
         Returns:
-            result (array, dict): The loaded array if ``.npy`` file or a dict mapping name to array if ``.npz`` file
+            result (array, dict):
+                A single array if loading from a ``.npy`` file or a dict mapping
+                names to arrays if loading from a ``.npz`` or ``.safetensors`` file.
+      )pbdoc");
+  m.def(
+      "save_safetensors",
+      &mlx_save_safetensor_helper,
+      "file"_a,
+      "arrays"_a,
+      py::pos_only(),
+      "retain_graph"_a = std::nullopt,
+      py::kw_only(),
+      R"pbdoc(
+        save_safetensors(file: str, arrays: Dict[str, array], /, retain_graph: Optional[bool] = None)
+
+        Save array(s) to a binary file in ``.safetensors`` format.
+
+        For more information on the format see https://huggingface.co/docs/safetensors/index.
+
+        Args:
+            file (file, str): File in which the array is saved>
+            arrays (dict(str, array)): The dictionary of names to arrays to be saved.
+            retain_graph (bool, optional): Whether or not to retain the graph
+              during array evaluation. If left unspecified the graph is retained
+              only if saving is done in a function transformation. Default: ``None``.
       )pbdoc");
   m.def(
       "where",

python/tests/test_load.py

@@ -64,6 +64,33 @@ class TestLoad(mlx_tests.MLXTestCase):
                         load_arr_mlx_npy = np.load(save_file_mlx)
                         self.assertTrue(np.array_equal(load_arr_mlx_npy, save_arr_npy))
 
+    def test_save_and_load_safetensors(self):
+        if not os.path.isdir(self.test_dir):
+            os.mkdir(self.test_dir)
+
+        for dt in self.dtypes + ["bfloat16"]:
+            with self.subTest(dtype=dt):
+                for i, shape in enumerate([(1,), (23,), (1024, 1024), (4, 6, 3, 1, 2)]):
+                    with self.subTest(shape=shape):
+                        save_file_mlx = os.path.join(
+                            self.test_dir, f"mlx_{dt}_{i}_fs.safetensors"
+                        )
+                        save_dict = {
+                            "test": mx.random.normal(shape=shape, dtype=getattr(mx, dt))
+                            if dt in ["float32", "float16", "bfloat16"]
+                            else mx.ones(shape, dtype=getattr(mx, dt))
+                        }
+
+                        with open(save_file_mlx, "wb") as f:
+                            mx.save_safetensors(f, save_dict)
+                        with open(save_file_mlx, "rb") as f:
+                            load_dict = mx.load(f)
+
+                        self.assertTrue("test" in load_dict)
+                        self.assertTrue(
+                            mx.array_equal(load_dict["test"], save_dict["test"])
+                        )
+
     def test_save_and_load_fs(self):
 
         if not os.path.isdir(self.test_dir):

tests/load_tests.cpp

@@ -14,6 +14,26 @@ std::string get_temp_file(const std::string& name) {
   return std::filesystem::temp_directory_path().append(name);
 }
 
+TEST_CASE("test save_safetensors") {
+  std::string file_path = get_temp_file("test_arr.safetensors");
+  auto map = std::unordered_map<std::string, array>();
+  map.insert({"test", array({1.0, 2.0, 3.0, 4.0})});
+  map.insert({"test2", ones({2, 2})});
+  save_safetensors(file_path, map);
+  auto safeDict = load_safetensors(file_path);
+  CHECK_EQ(safeDict.size(), 2);
+  CHECK_EQ(safeDict.count("test"), 1);
+  CHECK_EQ(safeDict.count("test2"), 1);
+  array test = safeDict.at("test");
+  CHECK_EQ(test.dtype(), float32);
+  CHECK_EQ(test.shape(), std::vector<int>({4}));
+  CHECK(array_equal(test, array({1.0, 2.0, 3.0, 4.0})).item<bool>());
+  array test2 = safeDict.at("test2");
+  CHECK_EQ(test2.dtype(), float32);
+  CHECK_EQ(test2.shape(), std::vector<int>({2, 2}));
+  CHECK(array_equal(test2, ones({2, 2})).item<bool>());
+}
+
 TEST_CASE("test single array serialization") {
   // Basic test
   {