Add missing merge clauses in DeltaTableWriter

src/koheesio/spark/writers/delta/batch.py

@@ -274,19 +274,8 @@ def _merge_builder_from_args(self):
             .merge(self.df.alias(source_alias), merge_cond)
         )
 
-        valid_clauses = [
-            "whenMatchedUpdate",
-            "whenNotMatchedInsert",
-            "whenMatchedDelete",
-            "whenNotMatchedBySourceUpdate",
-            "whenNotMatchedBySourceDelete",
-        ]
-
         for merge_clause in merge_clauses:
             clause_type = merge_clause.pop("clause", None)
-            if clause_type not in valid_clauses:
-                raise ValueError(f"Invalid merge clause '{clause_type}' provided")
-
             method = getattr(builder, clause_type)
             builder = method(**merge_clause)
 
@@ -314,6 +303,25 @@ def _validate_table(cls, table):
             return DeltaTableStep(table=table)
         return table
 
+    @field_validator("params")
+    def _validate_params(cls, params):
+        """Validates params. If an array of merge clauses is provided, they will be validated against the available
+        ones in DeltaMergeBuilder"""
+
+        valid_clauses = {m for m in dir(DeltaMergeBuilder) if m.startswith("when")}
+
+        if "merge_builder" in params:
+            merge_builder = params["merge_builder"]
+            if isinstance(merge_builder, list):
+                for merge_conf in merge_builder:
+                    clause = merge_conf.get("clause")
+                    if clause not in valid_clauses:
+                        raise ValueError(f"Invalid merge clause '{clause}' provided")
+            elif not isinstance(merge_builder, DeltaMergeBuilder):
+                raise ValueError("merge_builder must be a list or merge clauses or a DeltaMergeBuilder instance")
+
+        return params
+
     @classmethod
     def get_output_mode(cls, choice: str, options: Set[Type]) -> Union[BatchOutputMode, StreamingOutputMode]:
         """Retrieve an OutputMode by validating `choice` against a set of option OutputModes.

tests/spark/writers/delta/test_delta_writer.py

@@ -308,24 +308,25 @@ def test_merge_from_args(spark, dummy_df):
         )
 
 
-def test_merge_from_args_raise_value_error(spark, dummy_df):
-    table_name = "test_table_merge_from_args_value_error"
-    dummy_df.write.format("delta").saveAsTable(table_name)
-
-    writer = DeltaTableWriter(
-        df=dummy_df,
-        table=table_name,
-        output_mode=BatchOutputMode.MERGE,
-        output_mode_params={
+@pytest.mark.parametrize(
+    "output_mode_params",
+    [
+        {
             "merge_builder": [
                 {"clause": "NOT-SUPPORTED-MERGE-CLAUSE", "set": {"id": "source.id"}, "condition": "source.id=target.id"}
             ],
             "merge_cond": "source.id=target.id",
         },
-    )
-
+        {"merge_builder": MagicMock()},
+    ],
+)
+def test_merge_from_args_raise_value_error(spark, output_mode_params):
     with pytest.raises(ValueError):
-        writer._merge_builder_from_args()
+        DeltaTableWriter(
+            table="test_table_merge",
+            output_mode=BatchOutputMode.MERGE,
+            output_mode_params=output_mode_params,
+        )
 
 
 def test_merge_no_table(spark):