Add test of NNX with orbax.checkpoint

Author: jakevdp

jax_ml_stack/tests/test_nnx_with_optax.py

@@ -51,3 +51,6 @@ def loss(model, x=x, y=y):
     final_loss = loss(model)
 
     self.assertNotAlmostEqual(initial_loss, final_loss)
+
+if __name__ == '__main__':
+    unittest.main()

jax_ml_stack/tests/test_nnx_with_orbax.py

@@ -0,0 +1,70 @@
+# Copyright 2024 The JAX Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import unittest
+import numpy as np
+import jax
+import jax.numpy as jnp
+from flax import nnx
+import orbax.checkpoint as ocp
+
+
+class SimpleModel(nnx.Module):
+
+  def __init__(self, rngs):
+    self.layer1 = nnx.Linear(2, 5, rngs=rngs)
+    self.layer2 = nnx.Linear(5, 3, rngs=rngs)
+
+  def __call__(self, x):
+    for layer in [self.layer1, self.layer2]:
+      x = layer(x)
+    return x
+
+
+class NNXOrbaxTest(unittest.TestCase):
+  
+  def setUp(self):
+    options = ocp.CheckpointManagerOptions(
+        create=True, max_to_keep=3, keep_period=2, step_prefix='test')
+    self.manager = ocp.CheckpointManager(
+        ocp.test_utils.erase_and_create_empty('/tmp/test-checkpoint/'),
+        ocp.Checkpointer(ocp.PyTreeCheckpointHandler()),
+        options=options
+    )
+
+  def test_nnx_orbax_checkpoint(self):
+    key = jax.random.key(1701)
+    x = jax.random.normal(key, (1, 2))
+    y = jnp.ones((1, 3))
+
+    model = SimpleModel(nnx.Rngs(0))
+
+    # Create the checkpoint
+    graphdef, state = nnx.split(model)
+    abstract_state = jax.tree.map(ocp.utils.to_shape_dtype_struct, state)
+
+    restore_args = ocp.checkpoint_utils.construct_restore_args(abstract_state)
+    self.manager.save(0, state)
+    self.manager.wait_until_finished()
+
+    restored_state = self.manager.restore(
+        0, items=abstract_state, restore_kwargs={'restore_args': restore_args})
+    restored_model = nnx.merge(graphdef, restored_state)
+
+    self.assertEqual(type(model), type(restored_model))
+    jax.tree.map(np.testing.assert_array_equal, state, restored_state)
+
+if __name__ == '__main__':
+    unittest.main()