From 152e622af3989a7a17d4d2bab7464aeb984952aa Mon Sep 17 00:00:00 2001
From: Tim Head <betatim@gmail.com>
Date: Fri, 25 Nov 2022 13:49:11 +0100
Subject: [PATCH] Small fixes

---
 .../_hist_gradient_boosting/gradient_boosting.py       | 10 +++++++++-
 .../tests/test_gradient_boosting.py                    |  8 ++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/sklearn/ensemble/_hist_gradient_boosting/gradient_boosting.py b/sklearn/ensemble/_hist_gradient_boosting/gradient_boosting.py
index 66bd2b1f11d65..ba44532077bc1 100644
--- a/sklearn/ensemble/_hist_gradient_boosting/gradient_boosting.py
+++ b/sklearn/ensemble/_hist_gradient_boosting/gradient_boosting.py
@@ -93,7 +93,12 @@ class BaseHistGradientBoosting(BaseEstimator, ABC):
         "min_samples_leaf": [Interval(Integral, 1, None, closed="left")],
         "l2_regularization": [Interval(Real, 0, None, closed="left")],
         "monotonic_cst": ["array-like", dict, None],
-        "interaction_cst": [list, tuple, StrOptions({"pairwise", "no_interactions"}), None],
+        "interaction_cst": [
+            list,
+            tuple,
+            StrOptions({"pairwise", "no_interactions"}),
+            None,
+        ],
         "n_iter_no_change": [Interval(Integral, 1, None, closed="left")],
         "validation_fraction": [
             Interval(Real, 0, 1, closed="neither"),
@@ -295,6 +300,9 @@ def _check_interaction_cst(self, n_features):
         elif self.interaction_cst == "pairwise":
             interaction_cst = itertools.combinations(range(n_features), 2)
 
+        else:
+            interaction_cst = self.interaction_cst
+
         try:
             constraints = [set(group) for group in interaction_cst]
         except TypeError:
diff --git a/sklearn/ensemble/_hist_gradient_boosting/tests/test_gradient_boosting.py b/sklearn/ensemble/_hist_gradient_boosting/tests/test_gradient_boosting.py
index 6d8e01500a550..33c83de0959f7 100644
--- a/sklearn/ensemble/_hist_gradient_boosting/tests/test_gradient_boosting.py
+++ b/sklearn/ensemble/_hist_gradient_boosting/tests/test_gradient_boosting.py
@@ -1209,9 +1209,13 @@ def test_check_interaction_cst(interaction_cst, n_features, result):
         for combination in itertools.product(
             (HistGradientBoostingRegressor, HistGradientBoostingClassifier),
             (
-                ("no interactions", None),
+                ("no_interactions", None),
                 ("pairwise", None),
-                ("pairwiseS", "not a valid interaction constraint"),
+                (
+                    "pairwiseS",
+                    "a str among {'pairwise', 'no_interactions'} or None. Got"
+                    " 'pairwiseS' instead.",
+                ),
             ),
         )
     ],