From df22721efa628ae6223b1d49fb6688ff34b16eae Mon Sep 17 00:00:00 2001
From: Maaz Ali <maazali8460@gmail.com>
Date: Mon, 30 Mar 2026 10:43:17 +0500
Subject: [PATCH 1/3] [Fix] GridSearchCV scoring=None defaults to CRPS

If scoring= None, set it to CRPS().
---
 skpro/model_selection/_tuning.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/skpro/model_selection/_tuning.py b/skpro/model_selection/_tuning.py
index dbac1b22c..25e058910 100644
--- a/skpro/model_selection/_tuning.py
+++ b/skpro/model_selection/_tuning.py
@@ -8,6 +8,7 @@
 import pandas as pd
 from sklearn.model_selection import ParameterGrid, ParameterSampler, check_cv
 
+from skpro.metrics import CRPS
 from skpro.benchmarking.evaluate import evaluate
 from skpro.regression.base._delegate import _DelegatedProbaRegressor
 from skpro.utils.parallel import parallelize
@@ -108,6 +109,8 @@ def _fit(self, X, y, C=None):
 
         # scoring = check_scoring(self.scoring, obj=self)
         scoring = self.scoring
+        if scoring is None:
+            scoring = CRPS()
         scoring_name = f"test_{scoring.name}"
 
         backend = self.backend

From e81b17d12a308a15a2f86464e3a3adea679a7a72 Mon Sep 17 00:00:00 2001
From: Maaz Ali <maazali8460@gmail.com>
Date: Mon, 30 Mar 2026 15:19:26 +0500
Subject: [PATCH 2/3] [Fix] Supports backend in RandomizedSearchCV

Added backend parameter in RandomizedSearchCV constructor.
---
 skpro/model_selection/_tuning.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/skpro/model_selection/_tuning.py b/skpro/model_selection/_tuning.py
index 25e058910..8d8a79942 100644
--- a/skpro/model_selection/_tuning.py
+++ b/skpro/model_selection/_tuning.py
@@ -663,6 +663,7 @@ def __init__(
         verbose=0,
         return_n_best_estimators=1,
         random_state=None,
+        backend="loky",
         error_score=np.nan,
         backend_params=None,
     ):
@@ -673,6 +674,7 @@ def __init__(
             cv=cv,
             verbose=verbose,
             return_n_best_estimators=return_n_best_estimators,
+            backend=backend,
             error_score=error_score,
             backend_params=backend_params,
         )

From f1acab54c78bcc58e18eed41d5374bd8bb5e7f0b Mon Sep 17 00:00:00 2001
From: Maaz Ali <maazali8460@gmail.com>
Date: Wed, 29 Apr 2026 16:28:53 +0500
Subject: [PATCH 3/3]  Added a parameter set to get_test_params that sets
 backend explicitly to "none"

---
 skpro/model_selection/_tuning.py           |  6 ++--
 skpro/model_selection/tests/__init__.py    |  1 +
 skpro/model_selection/tests/test_tuning.py | 37 ++++++++++++++++++++++
 3 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 skpro/model_selection/tests/__init__.py
 create mode 100644 skpro/model_selection/tests/test_tuning.py

diff --git a/skpro/model_selection/_tuning.py b/skpro/model_selection/_tuning.py
index 8d8a79942..ec7c8b353 100644
--- a/skpro/model_selection/_tuning.py
+++ b/skpro/model_selection/_tuning.py
@@ -491,7 +491,8 @@ def get_test_params(cls, parameter_set="default"):
             "scoring": PinballLoss(),
             "error_score": "raise",
         }
-        params = [param1, param2, params3]
+        param_no_backend = {**param1, "backend": "None"}
+        params = [param1, param2, params3, param_no_backend]
 
         return params
 
@@ -737,6 +738,7 @@ def get_test_params(cls, parameter_set="default"):
             "scoring": PinballLoss(),
             "error_score": "raise",
         }
-        params = [param1, param2, params3]
+        param_no_backend = {**param1, "backend": "None"}
+        params = [param1, param2, params3, param_no_backend]
 
         return params
diff --git a/skpro/model_selection/tests/__init__.py b/skpro/model_selection/tests/__init__.py
new file mode 100644
index 000000000..90ba1208e
--- /dev/null
+++ b/skpro/model_selection/tests/__init__.py
@@ -0,0 +1 @@
+"""Tests for model selection utilities."""
\ No newline at end of file
diff --git a/skpro/model_selection/tests/test_tuning.py b/skpro/model_selection/tests/test_tuning.py
new file mode 100644
index 000000000..7adaaee85
--- /dev/null
+++ b/skpro/model_selection/tests/test_tuning.py
@@ -0,0 +1,37 @@
+"""Tests for model selection tuning utilities."""
+
+import pandas as pd
+import pytest
+from sklearn.model_selection import KFold
+
+from skpro.model_selection import GridSearchCV, RandomizedSearchCV
+from skpro.regression.dummy import DummyProbaRegressor
+from skpro.tests.test_switch import run_test_module_changed
+
+
+def _get_test_data():
+    X = pd.DataFrame({"x": [1, 2, 3, 4]})
+    y = pd.DataFrame({"y": [1.0, 2.0, 3.0, 4.0]})
+    return X, y
+
+
+@pytest.mark.skipif(
+    not run_test_module_changed("skpro.model_selection"),
+    reason="Test only if skpro.model_selection has been changed",
+)
+def test_randomizedsearch_accepts_backend_argument():
+    """RandomizedSearchCV should accept backend argument documented in API."""
+    X, y = _get_test_data()
+
+    rscv = RandomizedSearchCV(
+        estimator=DummyProbaRegressor(),
+        cv=KFold(n_splits=2),
+        param_distributions={"strategy": ["empirical"]},
+        n_iter=1,
+        scoring=None,
+        backend="threading",
+        backend_params={"n_jobs": 1},
+    )
+    rscv.fit(X, y)
+
+    assert rscv.backend == "threading"
\ No newline at end of file