test(ddl): add cross-backend DDL contracts and narrow the materialized-view contract

CLAUDE.md

@@ -110,3 +110,9 @@ git checkout as a development dependency.
    `python-activerecord-mysql`, etc.) and their `tests/` mirror trees.
 3. For provider interface contracts, browse
    `src/rhosocial/activerecord/testsuite/feature/<topic>/interfaces.py`.
+
+## Search Scope
+
+- Use `rg` for repository searches; never use `grep`.
+- Limit searches to this `python-activerecord` repository and its related testsuite/backend directories.
+- Exclude `.git/`, `.venv*/`, `__pycache__/`, `build/`, `dist/`, and other cache directories.

changelog.d/21.added.md

@@ -0,0 +1 @@
+Add cross-backend DDL contracts — a materialized-view contract requiring a dialect that advertises `supports_materialized_view()` to own its CREATE and refresh formatters, and a `DDLSource` collection contract covering retained sources — plus a `requires_cte_order_by` decorator and BMP-only Unicode round-trip tests.

changelog.d/21.changed.md

@@ -0,0 +1 @@
+Narrow the materialized-view contract to semantics every MV backend shares, stop treating MV refresh as a SQL-standard statement, and grade contract skips by whether the dialect can resolve a version. Adapt the expression tests to node-based casts and normalise timezone-aware datetimes.

changelog.d/21.removed.md

@@ -0,0 +1 @@
+Remove the deprecated `features.py` and the unused `sqlite_features.py`.

src/rhosocial/activerecord/testsuite/feature/basic/ddl/test_alter_table_if_exists.py

@@ -43,15 +43,15 @@ class TestDdlAddColumn:
     @requires_protocol(AlterTableModifierSupport, "supports_add_column_if_not_exists")
     def test_add_column_if_not_exists(self, ddl_dialect):
         """ALTER TABLE ADD COLUMN IF NOT EXISTS should render the IF NOT EXISTS qualifier."""
-        action = AddColumn(ddl_dialect, ColumnDefinition("content", TextType()), if_not_exists=True)
+        action = AddColumn(ddl_dialect, ColumnDefinition(ddl_dialect, "content", TextType(ddl_dialect)), if_not_exists=True)
         sql, params = action.to_sql()
         assert "IF NOT EXISTS" in sql, \
             "Expected the rendered SQL to contain the IF NOT EXISTS qualifier"
         assert not params, "Expected no bound parameters for ALTER TABLE ADD COLUMN"
 
     def test_add_column_plain_form(self, ddl_dialect):
         """ALTER TABLE ADD COLUMN without if_not_exists should omit the qualifier."""
-        action = AddColumn(ddl_dialect, ColumnDefinition("content", TextType()))
+        action = AddColumn(ddl_dialect, ColumnDefinition(ddl_dialect, "content", TextType(ddl_dialect)))
         sql, params = action.to_sql()
         assert "IF NOT EXISTS" not in sql, \
             "Expected the rendered SQL to omit the IF NOT EXISTS qualifier"

src/rhosocial/activerecord/testsuite/feature/basic/ddl/test_alter_table_if_exists_async.py

@@ -34,7 +34,7 @@ class TestAsyncDdlAddColumn:
     async def test_add_column_if_not_exists(self, async_ddl_dialect):
         """ALTER TABLE ADD COLUMN IF NOT EXISTS should render the IF NOT EXISTS qualifier."""
         action = AddColumn(
-            async_ddl_dialect, ColumnDefinition("content", TextType()), if_not_exists=True
+            async_ddl_dialect, ColumnDefinition(async_ddl_dialect, "content", TextType(async_ddl_dialect)), if_not_exists=True
         )
         sql, params = action.to_sql()
         assert "IF NOT EXISTS" in sql, \
@@ -43,7 +43,7 @@ async def test_add_column_if_not_exists(self, async_ddl_dialect):
 
     async def test_add_column_plain_form(self, async_ddl_dialect):
         """ALTER TABLE ADD COLUMN without if_not_exists should omit the qualifier."""
-        action = AddColumn(async_ddl_dialect, ColumnDefinition("content", TextType()))
+        action = AddColumn(async_ddl_dialect, ColumnDefinition(async_ddl_dialect, "content", TextType(async_ddl_dialect)))
         sql, params = action.to_sql()
         assert "IF NOT EXISTS" not in sql, \
             "Expected the rendered SQL to omit the IF NOT EXISTS qualifier"