Added explicit pathwaysutils.initialize() call to JetStream (#233)

Author: wstcliyu

jetstream/engine/__init__.py

@@ -15,9 +15,14 @@
 """Initialization for any Engine implementation."""
 
 import jax
+from importlib import util
 
-try:
+if util.find_spec("pathwaysutils"):
   import pathwaysutils
-except ImportError as e:
-  print("Proxy backend support is not added")
-  pass
+
+  pathwaysutils.initialize()
+else:
+  print(
+      "Running JetStream without Pathways. "
+      "Module pathwaysutils is not imported."
+  )

jetstream/tests/engine/test_init.py

@@ -0,0 +1,72 @@
+# Copyright 2024 Google LLC
+#
+# 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
+#
+#     http://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.
+
+"""Tests for initializing jetstream.engine module."""
+
+import contextlib
+import io
+import unittest
+from unittest import mock
+
+import importlib
+import jetstream.engine
+
+
+class InitTest(unittest.TestCase):
+
+  def test_init_with_error(self):
+    def mock_find_spec(name):
+      if name == "pathwaysutils":
+        return None
+      return "some_spec"
+
+    with mock.patch(
+        "importlib.util.find_spec", side_effect=mock_find_spec
+    ), contextlib.redirect_stdout(io.StringIO()) as captured_output:
+
+      importlib.reload(jetstream.engine)
+
+      self.assertIn(
+          "Running JetStream without Pathways.", captured_output.getvalue()
+      )
+
+  def test_init(self):
+    orig_import = __import__
+    p_mock = mock.Mock()
+
+    def mock_import(name, *args):
+
+      if name == "pathwaysutils":
+        return p_mock
+      return orig_import(name, *args)
+
+    def mock_find_spec(name):
+      if name == "pathwaysutils":
+        return "pathwaysutils_spec"
+      return "some_spec"
+
+    with mock.patch(
+        "importlib.util.find_spec", side_effect=mock_find_spec
+    ), mock.patch(
+        "builtins.__import__", side_effect=mock_import
+    ), contextlib.redirect_stdout(
+        io.StringIO()
+    ) as captured_output:
+      importlib.reload(jetstream.engine)
+
+      p_mock.initialize.assert_called_once()
+
+      self.assertNotIn(
+          "Running JetStream without Pathways.", captured_output.getvalue()
+      )