Run transport security tests in process instead of over sockets (#2764)

tests/interaction/transports/__init__.py

@@ -0,0 +1,9 @@
+"""Transport-specific interaction tests, and the in-process streaming bridge they are built on.
+
+`StreamingASGITransport` is re-exported here as the sanctioned import point for test code
+outside this suite (the bridge module itself is suite-private).
+"""
+
+from tests.interaction.transports._bridge import StreamingASGITransport
+
+__all__ = ["StreamingASGITransport"]