feat(snapshot): Squash commit with duplicate column validation

.changes/unreleased/Features-20240228-192518.yaml

@@ -0,0 +1,6 @@
+kind: Features
+body: Validation to detect duplicate column names in the check_cols configuration of a snapshot.
+time: 2024-02-28T19:25:18.00447-03:00
+custom:
+  Author: ariosramirez
+  Issue: "9656"

core/dbt/artifacts/resources/v1/snapshot.py

@@ -34,6 +34,12 @@ def final_validate(self):
                     f"Invalid value for 'check_cols': {self.check_cols}. "
                     "Expected 'all' or a list of strings."
                 )
+            # Validate if there are duplicate column names in check_cols.
+            if isinstance(self.check_cols, list):
+                if len(self.check_cols) != len(set(self.check_cols)):
+                    raise ValidationError(
+                        f"Duplicate column names in 'check_cols':" f" {self.check_cols}."
+                    )
         elif self.strategy == "timestamp":
             if not self.updated_at:
                 raise ValidationError(

tests/unit/contracts/graph/test_nodes_parsed.py

@@ -1481,6 +1481,16 @@ def assert_snapshot_config_fails_validation(dct):
         obj.final_validate()
 
 
+def test_duplicate_check_cols(basic_check_snapshot_config_dict):
+    duplicate_cols = basic_check_snapshot_config_dict
+    # Introducing duplicate column names
+    duplicate_cols["check_cols"] = ["col1", "col2", "col2"]
+    with pytest.raises(ValidationError, match=r"Duplicate column names in 'check_cols'"):
+        SnapshotConfig.validate(duplicate_cols)
+        cfg = SnapshotConfig.from_dict(duplicate_cols)
+        cfg.final_validate()
+
+
 def test_invalid_check_value(basic_check_snapshot_config_dict):
     invalid_check_type = basic_check_snapshot_config_dict
     invalid_check_type["check_cols"] = "some"