testlib: default nix fixture to also test all daemon protocols (3/3)

This is the real deal. The new tests have surfaced one bug in the test
suite itself, and one in the RPC legacy protocol wrapper.

Co-authored-by: eldritch horrors <pennae@lix.systems>
Change-Id: Id75b671c10b45655d3627abd88563e2d41719446

lix/libstore/daemon.cc

@@ -898,6 +898,7 @@ static void processLegacyRequests(
         debug("performing daemon worker op: %d", op);
 
         try {
+            KJ_DEFER(aio.blockOn(logger->flush()));
             performOp(aio, tunnelLogger, store, trusted, clientVersion, from, to, op);
         } catch (Error & e) {
             /* If we're not in a state where we can send replies, then

tests/functional2/daemon/test_rpc_setup.py

@@ -12,6 +12,7 @@ def test_legacy_sockets_always_appear(nix: Nix, daemon: NixDaemon):
         assert (sockets_dir / "socket").is_socket()
 
 
+@pytest.mark.no_daemon  # We do the daemon config ourselves here
 @pytest.mark.parametrize("daemon", ["legacy"], indirect=True)
 def test_xp_sockets_dont_always_appear(nix: Nix, daemon: NixDaemon):
     sockets_dir = nix.env.dirs.nix_state_dir / "daemon-socket"

tests/functional2/testlib/fixtures/nix.py

@@ -445,9 +445,7 @@ def pytest_generate_tests(metafunc: pytest.Metafunc):
     if "nix" not in metafunc.fixturenames or "daemon" in metafunc.fixturenames:
         return
     if not list(metafunc.definition.iter_markers("no_daemon")):
-        protocols = [None, "legacy-combined", "legacy"]
-        # do not enable them the protocols for now
-        # protocols += daemon_protocols # noqa ERA001
+        protocols = [None, *daemon_protocols]
         ids = protocols
         metafunc.parametrize("nix", protocols, indirect=True, ids=ids)