chore: import upstream snapshot with attribution

tensorflow/python/trackable/trackable_utils_test.py

@@ -0,0 +1,54 @@
+# Copyright 2021 The TensorFlow Authors. All Rights Reserved.
+#
+# 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 trackable_utils."""
+
+from tensorflow.python.eager import test
+from tensorflow.python.trackable import trackable_utils
+
+
+class TrackableUtilsTest(test.TestCase):
+
+  def test_order_by_dependency(self):
+    """Tests order_by_dependency correctness."""
+
+    # Visual graph (vertical lines point down, so 1 depends on 2):
+    #    1
+    #  /   \
+    # 2 --> 3 <-- 4
+    #       |
+    #       5
+    # One possible order: [5, 3, 4, 2, 1]
+    dependencies = {1: [2, 3], 2: [3], 3: [5], 4: [3], 5: []}
+
+    sorted_arr = list(trackable_utils.order_by_dependency(dependencies))
+    indices = {x: sorted_arr.index(x) for x in range(1, 6)}
+    self.assertEqual(indices[5], 0)
+    self.assertEqual(indices[3], 1)
+    self.assertGreater(indices[1], indices[2])  # 2 must appear before 1
+
+  def test_order_by_no_dependency(self):
+    sorted_arr = list(trackable_utils.order_by_dependency(
+        {x: [] for x in range(15)}))
+    self.assertEqual(set(sorted_arr), set(range(15)))
+
+  def test_order_by_dependency_invalid_map(self):
+    with self.assertRaisesRegex(
+        ValueError, "Found values in the dependency map which are not keys"):
+      trackable_utils.order_by_dependency({1: [2]})
+
+
+if __name__ == "__main__":
+  test.main()
+