test(model): roll back uncommitted ds_col mutations in timestamp-expression tests

tests/integration_tests/model_tests.py

@@ -395,47 +395,66 @@ class TestSqlaTableModel(SupersetTestCase):
     def test_get_timestamp_expression(self):
         tbl = self.get_table(name="birth_names")
         ds_col = tbl.get_column("ds")
-        sqla_literal = ds_col.get_timestamp_expression(None)
-        assert str(sqla_literal.compile()) == "ds"
-
-        sqla_literal = ds_col.get_timestamp_expression("P1D")
-        compiled = f"{sqla_literal.compile()}"
-        if tbl.database.backend == "mysql":
-            assert compiled == "DATE(ds)"
-
-        prev_ds_expr = ds_col.expression
-        ds_col.expression = "DATE_ADD(ds, 1)"
-        sqla_literal = ds_col.get_timestamp_expression("P1D")
-        compiled = f"{sqla_literal.compile()}"
-        if tbl.database.backend == "mysql":
-            assert compiled == "DATE(DATE_ADD(ds, 1))"
-        ds_col.expression = prev_ds_expr
+        try:
+            sqla_literal = ds_col.get_timestamp_expression(None)
+            assert str(sqla_literal.compile()) == "ds"
+
+            sqla_literal = ds_col.get_timestamp_expression("P1D")
+            compiled = f"{sqla_literal.compile()}"
+            if tbl.database.backend == "mysql":
+                assert compiled == "DATE(ds)"
+
+            prev_ds_expr = ds_col.expression
+            ds_col.expression = "DATE_ADD(ds, 1)"
+            sqla_literal = ds_col.get_timestamp_expression("P1D")
+            compiled = f"{sqla_literal.compile()}"
+            if tbl.database.backend == "mysql":
+                assert compiled == "DATE(DATE_ADD(ds, 1))"
+            ds_col.expression = prev_ds_expr
+        finally:
+            # Discard the in-memory attribute history so the next session
+            # autoflush doesn't see this row as dirty. The test only
+            # exercises the in-memory compile path; any persisted write
+            # would be accidental. ``rollback`` rather than ``expire`` —
+            # the latter doesn't reliably clear SA's per-attribute history
+            # tracking for already-loaded objects.
+            metadata_db.session.rollback()
 
     @pytest.mark.usefixtures("load_birth_names_dashboard_with_slices")
     def test_get_timestamp_expression_epoch(self):
         tbl = self.get_table(name="birth_names")
         ds_col = tbl.get_column("ds")
 
-        ds_col.expression = None
-        ds_col.python_date_format = "epoch_s"
-        sqla_literal = ds_col.get_timestamp_expression(None)
-        compiled = f"{sqla_literal.compile()}"
-        if tbl.database.backend == "mysql":
-            assert compiled == "from_unixtime(ds)"
-
-        ds_col.python_date_format = "epoch_s"
-        sqla_literal = ds_col.get_timestamp_expression("P1D")
-        compiled = f"{sqla_literal.compile()}"
-        if tbl.database.backend == "mysql":
-            assert compiled == "DATE(from_unixtime(ds))"
-
-        prev_ds_expr = ds_col.expression
-        ds_col.expression = "DATE_ADD(ds, 1)"
-        sqla_literal = ds_col.get_timestamp_expression("P1D")
-        compiled = f"{sqla_literal.compile()}"
-        if tbl.database.backend == "mysql":
-            assert compiled == "DATE(from_unixtime(DATE_ADD(ds, 1)))"
-        ds_col.expression = prev_ds_expr
+        try:
+            ds_col.expression = None
+            ds_col.python_date_format = "epoch_s"
+            sqla_literal = ds_col.get_timestamp_expression(None)
+            compiled = f"{sqla_literal.compile()}"
+            if tbl.database.backend == "mysql":
+                assert compiled == "from_unixtime(ds)"
+
+            ds_col.python_date_format = "epoch_s"
+            sqla_literal = ds_col.get_timestamp_expression("P1D")
+            compiled = f"{sqla_literal.compile()}"
+            if tbl.database.backend == "mysql":
+                assert compiled == "DATE(from_unixtime(ds))"
+
+            prev_ds_expr = ds_col.expression
+            ds_col.expression = "DATE_ADD(ds, 1)"
+            sqla_literal = ds_col.get_timestamp_expression("P1D")
+            compiled = f"{sqla_literal.compile()}"
+            if tbl.database.backend == "mysql":
+                assert compiled == "DATE(from_unixtime(DATE_ADD(ds, 1)))"
+            ds_col.expression = prev_ds_expr
+        finally:
+            # Discard the in-memory attribute history so the next session
+            # autoflush doesn't see this row as dirty —
+            # ``python_date_format`` isn't restored above and the test
+            # never commits, so the mutation would otherwise leak.
+            # ``rollback`` rather than ``expire`` — the latter doesn't
+            # reliably clear SA's per-attribute history tracking for
+            # already-loaded objects.
+            metadata_db.session.rollback()
 
     def query_with_expr_helper(self, is_timeseries, inner_join=True):
         tbl = self.get_table(name="birth_names")