fix(testing): MockContext ignores its dialect argument #399

MockContext.__post_init__ (src/strawchemy/testing/__init__.py:19) sets dialect.name = "postgresql" whatever dialect is given, so its dialect field is never read.

MockContext("sqlite").session.get_bind().dialect.name  # "postgresql"

This predates the pytest plugin removal (d1d5bbf); the old pytest_plugin.py did the same. Every test passes "postgresql", so nothing catches it.

Fix: use self.dialect. Now that the plugin is gone, it may also be worth deciding whether MockContext stays public.