test: add pseudo transport explicitly rather than by setting ConfiguredAddr

ConfiguredAddr is going to be removed, but we need to be able to add fake transports,
also for existing offline Python tests.

python/src/deltachat/testplugin.py

@@ -11,6 +11,9 @@ import random
 from queue import Queue
 from typing import Callable, Dict, List, Optional
 
+from .capi import lib
+from .cutil import as_dc_charpointer
+
 import pytest
 from _pytest._code import Source
 
@@ -366,6 +369,7 @@ class ACFactory:
             ac.open(passphrase)
         acname = ac._logid
         addr = f"{acname}@offline.org"
+        lib.dc_add_pseudo_transport(ac._dc_context, as_dc_charpointer(addr))
         ac.update_config(
             {
                 "configured_addr": addr,
@@ -374,6 +378,7 @@ class ACFactory:
         )
         self._preconfigure_key(ac)
         self._acsetup.init_logging(ac)
+        assert ac.is_configured(), "Pseudo configured account should look like if it is configured"
         return ac
 
     def new_online_configuring_account(self, cloned_from=None, **kwargs) -> Account: