Cast resample_probability before range check in PBT validation (#2685)

PBT's ValidateAlgorithmSettings compares resample_probability against
0 and 1 without casting it, but algorithm setting values arrive as
strings. The comparison raises TypeError and the validation crashes with
an internal error instead of returning a clear message, unlike the
adjacent n_population and truncation_threshold checks which cast first.
Cast the value with float, matching those checks, and add a PBT service
test covering the validation (the service had no unit test before).

Signed-off-by: Saivedant Hava <saivedant169@gmail.com>

Author: saivedant169

pkg/suggestion/v1beta1/pbt/service.py

@@ -66,7 +66,7 @@ def ValidateAlgorithmSettings(self, request, context):
             )
         if (
             "resample_probability" in settings
-            and not 0 <= settings["resample_probability"] <= 1
+            and not 0 <= float(settings["resample_probability"]) <= 1
         ):
             return self._set_validate_context_error(
                 context,

test/unit/v1beta1/suggestion/test_pbt_service.py

@@ -0,0 +1,72 @@
+# Copyright 2026 The Kubeflow 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
+
+import grpc
+import grpc_testing
+import utils
+
+from pkg.apis.manager.v1beta1.python import api_pb2
+from pkg.suggestion.v1beta1.pbt.service import PbtService
+
+
+class TestPbt(unittest.TestCase):
+    def setUp(self):
+        servicers = {
+            api_pb2.DESCRIPTOR.services_by_name["Suggestion"]: PbtService()
+        }
+        self.test_server = grpc_testing.server_from_dictionary(
+            servicers, grpc_testing.strict_real_time()
+        )
+
+    def _spec(self, resample_probability=None):
+        settings = [
+            api_pb2.AlgorithmSetting(name="suggestion_trial_dir", value="/tmp"),
+            api_pb2.AlgorithmSetting(name="n_population", value="10"),
+            api_pb2.AlgorithmSetting(name="truncation_threshold", value="0.2"),
+        ]
+        if resample_probability is not None:
+            settings.append(
+                api_pb2.AlgorithmSetting(
+                    name="resample_probability", value=resample_probability
+                )
+            )
+        return api_pb2.ExperimentSpec(
+            algorithm=api_pb2.AlgorithmSpec(
+                algorithm_name="pbt", algorithm_settings=settings
+            )
+        )
+
+    def test_validate_algorithm_settings(self):
+        # Valid, without the optional resample_probability.
+        _, _, code, _ = utils.call_validate(self.test_server, self._spec())
+        self.assertEqual(code, grpc.StatusCode.OK)
+
+        # Valid, with a resample_probability inside [0, 1]. Its value arrives as a
+        # string, so the range check must cast it before comparing.
+        _, _, code, _ = utils.call_validate(
+            self.test_server, self._spec(resample_probability="0.5")
+        )
+        self.assertEqual(code, grpc.StatusCode.OK)
+
+        # Invalid, resample_probability outside [0, 1].
+        _, _, code, _ = utils.call_validate(
+            self.test_server, self._spec(resample_probability="1.5")
+        )
+        self.assertEqual(code, grpc.StatusCode.INVALID_ARGUMENT)
+
+
+if __name__ == "__main__":
+    unittest.main()