Allow infinite retries for workflows

ext/dapr-ext-workflow/dapr/ext/workflow/retry_policy.py

@@ -40,6 +40,7 @@ def __init__(
         Args:
             first_retry_interval(timedelta): The retry interval to use for the first retry attempt.
             max_number_of_attempts(int):  The maximum number of retry attempts.
+                Use ``-1`` for infinite retries.
             backoff_coefficient(Optional[float]): The backoff coefficient to use for calculating
                 the next retry interval.
             max_retry_interval(Optional[timedelta]): The maximum retry interval to use for any
@@ -50,8 +51,8 @@ def __init__(
         # validate inputs
         if first_retry_interval < timedelta(seconds=0):
             raise ValueError('first_retry_interval must be >= 0')
-        if max_number_of_attempts < 1:
-            raise ValueError('max_number_of_attempts must be >= 1')
+        if max_number_of_attempts == 0 or max_number_of_attempts < -1:
+            raise ValueError('max_number_of_attempts must be >= 1 or -1 for infinite retries')
         if backoff_coefficient is not None and backoff_coefficient < 1:
             raise ValueError('backoff_coefficient must be >= 1')
         if max_retry_interval is not None and max_retry_interval < timedelta(seconds=0):

ext/dapr-ext-workflow/tests/test_retry_policy.py

@@ -0,0 +1,35 @@
+# -*- coding: utf-8 -*-
+
+"""
+Copyright 2023 The Dapr 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
+    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.
+"""
+
+import unittest
+from datetime import timedelta
+
+from dapr.ext.workflow.retry_policy import RetryPolicy
+
+
+class RetryPolicyTests(unittest.TestCase):
+    def test_allow_infinite_max_number_of_attempts(self):
+        retry_policy = RetryPolicy(
+            first_retry_interval=timedelta(seconds=1), max_number_of_attempts=-1
+        )
+
+        self.assertEqual(-1, retry_policy.max_number_of_attempts)
+
+    def test_reject_invalid_max_number_of_attempts(self):
+        with self.assertRaises(ValueError):
+            RetryPolicy(first_retry_interval=timedelta(seconds=1), max_number_of_attempts=0)
+
+        with self.assertRaises(ValueError):
+            RetryPolicy(first_retry_interval=timedelta(seconds=1), max_number_of_attempts=-2)