fixes subquery table adapter test

docs/website/docs/dlt-ecosystem/verified-sources/sql_database/usage.md

@@ -93,14 +93,15 @@ table = sql_table(
 You can add computed columns to the table definition by converting it into a subquery:
 ```py
 def add_max_timestamp(table):
-    computed_max_timestamp = sa.func.greatest(table.c.created_at, table.c.updated_at).label('max_timestamp')
-    subquery = sa.select(
-        [table, computed_max_timestamp]
-    ).subquery()
+    computed_max_timestamp = sa.sql.type_coerce(
+        sa.func.greatest(table.c.created_at, table.c.updated_at),
+        sqltypes.DateTime,
+    ).label("max_timestamp")
+    subquery = sa.select(*table.c, computed_max_timestamp).subquery()
     return subquery
 ```
-We add new `max_timestamp` column that is a MIN of `created_at` and `updated_at` columns and then convert it into a subquery
-because we intend to use it for incremental loading.
+We add new `max_timestamp` column that is a MAX of `created_at` and `updated_at` columns and then we convert it into a subquery
+because we intend to use it for incremental loading which will attach a `WHERE` clause to it.
 
 ```py
 import dlt

tests/common/test_utils.py

@@ -407,7 +407,7 @@ def test_group_dict_of_lists_various_length_lists():
     assert sizes == sorted(sizes, reverse=True), "Sizes of decomposed dicts are not decreasing"
 
 
-def function_test(a, b):
+def function_typeerror_exc(a, b):
     raise TypeError("wrong type")
 
 
@@ -431,12 +431,12 @@ def _function_test(a, *, b=None):
         assert is_typeerror_due_to_wrong_call(exc, _function_test) is False
 
     try:
-        function_test()  # type: ignore[call-arg]
+        function_typeerror_exc()  # type: ignore[call-arg]
     except Exception as exc:
-        assert is_typeerror_due_to_wrong_call(exc, function_test) is True
+        assert is_typeerror_due_to_wrong_call(exc, function_typeerror_exc) is True
 
     try:
-        function_test("a", "b")
+        function_typeerror_exc("a", "b")
     except Exception as exc:
         assert str(exc) == "wrong type"
-        assert is_typeerror_due_to_wrong_call(exc, function_test) is False
+        assert is_typeerror_due_to_wrong_call(exc, function_typeerror_exc) is False

tests/load/sources/sql_database/test_sql_database_source.py

@@ -275,14 +275,15 @@ def query_adapter(
 
 @pytest.mark.parametrize("backend", ["sqlalchemy", "pandas", "pyarrow"])
 def test_computed_column(sql_source_db: SQLAlchemySourceDB, backend: TableBackend) -> None:
-    from dlt.common.libs.sql_alchemy import Table, sa
+    from dlt.common.libs.sql_alchemy import Table, sa, sqltypes
     from dlt.sources.sql_database.helpers import SelectAny
 
     def add_max_timestamp(table: Table) -> SelectAny:
-        computed_max_timestamp = sa.func.greatest(table.c.created_at, table.c.updated_at).label(
-            "max_timestamp"
-        )
-        subquery = sa.select([table, computed_max_timestamp]).subquery()
+        computed_max_timestamp = sa.sql.type_coerce(
+            sa.func.greatest(table.c.created_at, table.c.updated_at),
+            sqltypes.DateTime,
+        ).label("max_timestamp")
+        subquery = sa.select(*table.c, computed_max_timestamp).subquery()
         return subquery
 
     read_table = sql_table(