Start a very basic ipc-server unit test suite

For now it just boots a server, parametrized over all tpt-protos, sin
any actor runtime bootup. Obvi the future todo is ensuring it all works
with a client connecting via the equivalent lowlevel
`.ipc._chan._connect_chan()` API(s).

tests/ipc/__init__.py

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+'''
+`tractor.ipc` subsystem(s)/unit testing suites.
+
+'''

tests/ipc/test_server.py

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+'''
+High-level `.ipc._server` unit tests.
+
+'''
+from __future__ import annotations
+
+import pytest
+import trio
+from tractor import (
+    devx,
+    ipc,
+    log,
+)
+from tractor._testing.addr import (
+    get_rando_addr,
+)
+# TODO, use/check-roundtripping with some of these wrapper types?
+#
+# from .._addr import Address
+# from ._chan import Channel
+# from ._transport import MsgTransport
+# from ._uds import UDSAddress
+# from ._tcp import TCPAddress
+
+
+@pytest.mark.parametrize(
+    '_tpt_proto',
+    ['uds', 'tcp']
+)
+def test_basic_ipc_server(
+    _tpt_proto: str,
+    debug_mode: bool,
+    loglevel: str,
+):
+
+    # so we see the socket-listener reporting on console
+    log.get_console_log("INFO")
+
+    rando_addr: tuple = get_rando_addr(
+        tpt_proto=_tpt_proto,
+    )
+    async def main():
+        async with ipc._server.open_ipc_server() as server:
+
+            assert (
+                server._parent_tn
+                and
+                server._parent_tn is server._stream_handler_tn
+            )
+            assert server._no_more_peers.is_set()
+
+            eps: list[ipc.IPCEndpoint] = await server.listen_on(
+                accept_addrs=[rando_addr],
+                stream_handler_nursery=None,
+            )
+            assert (
+                len(eps) == 1
+                and
+                (ep := eps[0])._listener
+                and
+                not ep.peer_tpts
+            )
+
+            server._parent_tn.cancel_scope.cancel()
+
+        # !TODO! actually make a bg-task connection from a client
+        # using `ipc._chan._connect_chan()`
+
+    with devx.maybe_open_crash_handler(
+        pdb=debug_mode,
+    ):
+        trio.run(main)