fix: CROSS JOIN from_linter edge registration, add warning + rollback tests

- CROSS JOIN now registers edges with from_linter instead of suppressing
  it entirely — preserves cartesian-product warnings for genuinely
  disconnected FROM elements while suppressing false positives
- Added CROSS JOIN warning contract regression test
- Added graph rollback no-op test (do_rollback swallows NotSupportedError)
- Added *.xlsx.lock to .gitignore
- Removed stale lock file artifacts

Author: yeongseon

.gitignore

@@ -42,3 +42,4 @@ Thumbs.db
 # Test artifacts
 *.xlsx
 !tests/fixtures/*.xlsx
+*.xlsx.lock

src/sqlalchemy_excel/compiler.py

@@ -35,6 +35,7 @@
 
 from __future__ import annotations
 
+import itertools
 import re
 from typing import TYPE_CHECKING, Any, Literal, cast
 
@@ -383,21 +384,30 @@ def visit_join(
             and not join.full
             and not join.isouter
         ):
-            # Intentional cartesian product -- suppress from_linter to
-            # avoid SAWarning about missing join conditions.
+            # Intentional cartesian product — register edges so the
+            # FROM-linter treats both sides as connected (no spurious
+            # SAWarning) while still detecting genuinely disconnected
+            # FROM elements elsewhere in the statement.
+            if from_linter:
+                from_linter.edges.update(
+                    itertools.product(
+                        join.left._from_objects,
+                        join.right._from_objects,
+                    )
+                )
             left = str(
                 join.left._compiler_dispatch(
                     self,
                     asfrom=True,
-                    from_linter=None,
+                    from_linter=from_linter,
                     **kwargs,
                 )
             )
             right = str(
                 join.right._compiler_dispatch(
                     self,
                     asfrom=True,
-                    from_linter=None,
+                    from_linter=from_linter,
                     **kwargs,
                 )
             )

tests/test_compiler_guards.py

@@ -1649,3 +1649,36 @@ def test_strip_compound_branch_parens_double_wrapped_grouped() -> None:
     result = ExcelCompiler._strip_compound_branch_parens(double_wrapped)
     # Passes through completely unchanged.
     assert result == double_wrapped
+
+
+def test_cross_join_no_sa_warning(tmp_xlsx: str) -> None:
+    """CROSS JOIN must not emit SAWarning about cartesian products."""
+    import warnings
+
+    import sqlalchemy as sa
+    from sqlalchemy import Column, Integer, MetaData, String, Table, create_engine
+
+    engine = create_engine(f"excel:///{tmp_xlsx}")
+    meta = MetaData()
+    t1 = Table("a", meta, Column("id", Integer), Column("x", String))
+    t2 = Table("b", meta, Column("id", Integer), Column("y", String))
+    meta.create_all(engine)
+    with engine.connect() as conn:
+        conn.execute(t1.insert(), [{"id": 1, "x": "v"}])
+        conn.execute(t2.insert(), [{"id": 1, "y": "w"}])
+        conn.commit()
+
+    with warnings.catch_warnings(record=True) as caught:
+        warnings.simplefilter("always")
+        with engine.connect() as conn:
+            j = t1.join(t2, sa.true())
+            stmt = sa.select(t1.c.id, t2.c.y).select_from(j)
+            rows = conn.execute(stmt).fetchall()
+            assert rows == [(1, "w")]
+
+    cartesian_warnings = [
+        w for w in caught if "cartesian" in str(w.message).lower()
+    ]
+    assert cartesian_warnings == [], (
+        f"CROSS JOIN should not emit cartesian warning: {cartesian_warnings}"
+    )

tests/test_graph_dialect.py

@@ -169,3 +169,22 @@ def test_select_with_where(self):
             assert len(rows) == 1
             assert rows[0] == ("Alice",)
         engine.dispose()
+
+
+class TestGraphRollbackNoOp:
+    """do_rollback should swallow NotSupportedError on graph connections."""
+
+    def test_rollback_is_noop_on_graph(self):
+        """Graph backend connections treat rollback as no-op."""
+        transport = httpx.MockTransport(_graph_handler)
+        engine = create_engine(
+            "excel+graph:///drv-test/itm-test",
+            connect_args={
+                "credential": "test-token",
+                "transport": transport,
+            },
+        )
+        with engine.connect() as conn:
+            # Rollback should not raise — dialect swallows NotSupportedError
+            conn.rollback()
+        engine.dispose()