Add tests

Differential Revision: [D85902974](https://our.internmc.facebook.com/intern/diff/D85902974/)

ghstack-source-id: 319923727
Pull Request resolved: #15482

Author: lucylq

exir/_serialize/test/TARGETS

@@ -43,3 +43,14 @@ python_unittest(
         "//executorch/exir/_serialize:lib",
     ],
 )
+
+python_unittest(
+    name = "test_serialize",
+    srcs = [
+        "test_serialize.py",
+    ],
+    deps = [
+        "//executorch/exir:lib",
+        "//executorch/exir/_serialize:lib",
+    ],
+)

exir/_serialize/test/test_serialize.py

@@ -0,0 +1,50 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# pyre-strict
+
+import unittest
+
+import torch
+from executorch.exir import (
+    EdgeCompileConfig,
+    ExecutorchBackendConfig,
+    ExecutorchProgramManager,
+    to_edge,
+)
+from executorch.exir._serialize._named_data_store import NamedDataStore
+from executorch.exir._serialize.data_serializer import DataEntry
+from executorch.exir._serialize._serialize import serialize_for_executorch
+from executorch.exir.scalar_type import ScalarType
+from executorch.exir.tensor_layout import TensorLayout
+
+from executorch.extension.flat_tensor.serialize.serialize import FlatTensorSerializer
+
+class TestSerialize(unittest.TestCase):
+    # Test serialize_for_executorch
+    # When we have data in PTD
+    # When we have NamedData in PTE
+    # When we have TensorLayouts.
+    # Also test pybindings.
+
+    def test_linear(self) -> None:
+        class LinearModule(torch.nn.Module):
+            def __init__(self):
+                super().__init__()
+                self.linear = torch.nn.Linear(5, 5)
+
+            def forward(self, x):
+                return self.linear(x)
+
+        config = ExecutorchBackendConfig(external_constants=True)
+        model = to_edge(
+            torch.export.export(LinearModule(), (torch.ones(5, 5),), strict=True)
+        ).to_executorch(config=config)
+        pte, ptds = serialize_for_executorch(model._emitter_output, config, FlatTensorSerializer(), named_data_store=model._named_data)
+
+        self.assertEqual(len(ptds), 1)
+        # Check that
+