fix(tests): fix sqlite migrator backup and restore test

On Windows, we must ensure the connection to the database is closed before exiting the tempfile context.

Also, rejiggered the thing to use the file directly.

tests/test_sqlite_migrator.py

@@ -99,23 +99,35 @@ def test_run_migrations(migrator: SQLiteMigrator):
     assert migrator._get_current_version() == 3
 
 
-def test_backup_and_restore_db(migrator: SQLiteMigrator):
+def test_backup_and_restore_db():
+    # must do this with a file database - we don't backup/restore for memory
     with TemporaryDirectory() as tempdir:
-        # must do this with a file database - we don't backup/restore for memory
+        # create test DB w/ some data
         database = Path(tempdir) / "test.db"
-        migrator._database = database
-        migrator._cursor.execute("CREATE TABLE test (id INTEGER PRIMARY KEY);")
-        migrator._conn.commit()
+        conn = sqlite3.connect(database, check_same_thread=False)
+        cursor = conn.cursor()
+        cursor.execute("CREATE TABLE test (id INTEGER PRIMARY KEY);")
+        conn.commit()
+
+        migrator = SQLiteMigrator(conn=conn, database=database, lock=threading.RLock(), logger=Logger("test"))
         backup_path = migrator._backup_db(migrator._database)
+
+        # mangle the db
         migrator._cursor.execute("DROP TABLE test;")
         migrator._conn.commit()
-        migrator._restore_db(backup_path)  # this closes the connection
-        # reconnect to db
+        migrator._cursor.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='test';")
+        assert migrator._cursor.fetchone() is None
+
+        # restore (closes the connection - must create a new one)
+        migrator._restore_db(backup_path)
         restored_conn = sqlite3.connect(database)
         restored_cursor = restored_conn.cursor()
         restored_cursor.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='test';")
         assert restored_cursor.fetchone() is not None
 
+        # must manually close else tempfile throws on cleanup on windows
+        restored_conn.close()
+
 
 def test_no_backup_and_restore_for_memory_db(migrator: SQLiteMigrator):
     with pytest.raises(MigrationError, match="Cannot back up memory database"):