Expose to/from fp8 in Python and don't auto-convert fp8 when loading from safetensors (#2985)

python/tests/test_load.py

@@ -168,8 +168,8 @@ class TestLoad(mlx_tests.MLXTestCase):
 
         expected = [
             0,
-            mx.nan,
-            mx.nan,
+            448,
+            -448,
             -0.875,
             0.4375,
             -0.005859,
@@ -179,12 +179,12 @@ class TestLoad(mlx_tests.MLXTestCase):
             -0.0039,
         ]
         expected = mx.array(expected, dtype=mx.bfloat16)
-        contents = b'H\x00\x00\x00\x00\x00\x00\x00{"tensor":{"dtype":"F8_E4M3","shape":[10],"data_offsets":[0,10]}}       \x00\x7f\xff\xb6.\x83\xba\xba\xbc\x82'
+        contents = b'H\x00\x00\x00\x00\x00\x00\x00{"tensor":{"dtype":"F8_E4M3","shape":[10],"data_offsets":[0,10]}}       \x00~\xfe\xb6.\x83\xba\xba\xbc\x82'
         with tempfile.NamedTemporaryFile(suffix=".safetensors") as f:
             f.write(contents)
             f.seek(0)
             out = mx.load(f)["tensor"]
-        self.assertTrue(mx.allclose(out[0], expected[0], equal_nan=True))
+        self.assertTrue(mx.allclose(mx.from_fp8(out), expected))
 
     def test_save_and_load_gguf_metadata_basic(self):
         if not os.path.isdir(self.test_dir):