[python-package] Add test for converting a ctypes int64 pointer array to a NumPy array

tests/python_package_test/test_engine.py

@@ -2013,6 +2013,31 @@ def test_contribs_sparse_multiclass():
         np.testing.assert_allclose(contribs_csc_array, contribs_dense)
 
 
+def test_predict_contrib_int64():
+    n_samples = 100
+    n_features = 5
+
+    X, y = make_multilabel_classification(
+        n_samples=n_samples, sparse=True, n_features=n_features, n_classes=1, n_labels=2
+    )
+    y = y.flatten()
+    X_train, X_test, y_train, _ = train_test_split(X, y, test_size=0.1, random_state=42)
+    X_test.indptr = X_test.indptr.astype(np.int64)
+
+    train_data = lgb.Dataset(X_train, label=y_train)
+    params = {"objective": "binary", "num_leaves": 7, "learning_rate": 0.1, "verbose": -1}
+    booster = lgb.Booster(params, train_data)
+
+    for _ in range(5):
+        booster.update()
+
+    preds = booster.predict(X_test, pred_contrib=True, num_iteration=booster.best_iteration)
+
+    assert preds is not None
+    assert preds.shape[0] == X_test.shape[0]
+    assert preds.shape[1] == X_test.shape[1] + 1
+
+
 # @pytest.mark.skipif(psutil.virtual_memory().available / 1024 / 1024 / 1024 < 3, reason="not enough RAM")
 # def test_int32_max_sparse_contribs(rng):
 #     params = {"objective": "binary"}