[spark] Add validation for param 'early_stopping_rounds' and 'validation_indicator_col'

python-package/xgboost/spark/core.py

@@ -295,6 +295,15 @@ def _validate_params(self):
             if not isinstance(self.getOrDefault(self.eval_metric), str):
                 raise ValueError("Only string type 'eval_metric' param is allowed.")
 
+        if self.isDefined(self.early_stopping_rounds):
+            if not (
+                self.isDefined(self.validationIndicatorCol) and self.getOrDefault(self.validationIndicatorCol)
+            ):
+                raise ValueError(
+                    "If 'early_stopping_rounds' param is set, you need to set "
+                    "'validation_indicator_col' param as well."
+                )
+
         if self.getOrDefault(self.enable_sparse_data_optim):
             if self.getOrDefault(self.missing) != 0.0:
                 # If DMatrix is constructed from csr / csc matrix, then inactive elements

tests/python/test_spark/test_spark_local.py

@@ -1145,3 +1145,8 @@ def test_empty_partition(self):
             num_workers=4,
         )
         classifier.fit(data_trans)
+
+    def test_early_stop_param_validation(self):
+        classifier = SparkXGBClassifier(early_stopping_rounds=1)
+        with pytest.raises(ValueError):
+            classifier.fit(self.cls_df_train)