Add an `enable_transports` test-suite

Like it sounds, verifying that when that param is passed to the runtime
startup eps (`.open_root_actor()/.open_nursery()`), the appropriate
tpt-protocol is deployed for IPC (both the server and bound endpoints)
in both the root and any sub-actors (as passed down from rent to child
via the `.msg.types.SpawnSpec`).

tests/ipc/test_multi_tpt.py

@@ -0,0 +1,95 @@
+'''
+Verify the `enable_transports` param drives various
+per-root/sub-actor IPC endpoint/server settings.
+
+'''
+from __future__ import annotations
+
+import pytest
+import trio
+import tractor
+from tractor import (
+    Actor,
+    Portal,
+    ipc,
+    msg,
+    _state,
+    _addr,
+)
+
+@tractor.context
+async def chk_tpts(
+    ctx: tractor.Context,
+    tpt_proto_key: str,
+):
+    rtvars = _state._runtime_vars
+    assert (
+        tpt_proto_key
+        in
+        rtvars['_enable_tpts']
+    )
+    actor: Actor = tractor.current_actor()
+    spec: msg.types.SpawnSpec = actor._spawn_spec
+    assert spec._runtime_vars == rtvars
+
+    # ensure individual IPC ep-addr types
+    serv: ipc._server.Server = actor.ipc_server
+    addr: ipc._types.Address
+    for addr in serv.addrs:
+        assert addr.proto_key == tpt_proto_key
+
+    # Actor delegate-props enforcement
+    assert (
+        actor.accept_addrs
+        ==
+        serv.accept_addrs
+    )
+
+    await ctx.started(serv.accept_addrs)
+
+
+# TODO, parametrize over mis-matched-proto-typed `registry_addrs`
+# since i seems to work in `piker` but not exactly sure if both tcp
+# & uds are being deployed then?
+#
+@pytest.mark.parametrize(
+    'tpt_proto_key',
+    ['tcp', 'uds'],
+    ids=lambda item: f'ipc_tpt={item!r}'
+)
+def test_root_passes_tpt_to_sub(
+    tpt_proto_key: str,
+    reg_addr: tuple,
+    debug_mode: bool,
+):
+    async def main():
+        async with tractor.open_nursery(
+            enable_transports=[tpt_proto_key],
+            registry_addrs=[reg_addr],
+            debug_mode=debug_mode,
+        ) as an:
+
+            assert (
+                tpt_proto_key
+                in
+                _state._runtime_vars['_enable_tpts']
+            )
+
+            ptl: Portal = await an.start_actor(
+                name='sub',
+                enable_modules=[__name__],
+            )
+            async with ptl.open_context(
+                chk_tpts,
+                tpt_proto_key=tpt_proto_key,
+            ) as (ctx, accept_addrs):
+
+                uw_addr: tuple
+                for uw_addr in accept_addrs:
+                    addr = _addr.wrap_address(uw_addr)
+                    assert addr.is_valid
+
+            # shudown sub-actor(s)
+            await an.cancel()
+
+    trio.run(main)