tests: cover in-process XIM lifecycle

tests/ipc_live_test.c

@@ -236,7 +236,8 @@ startdaemon(Daemon *d, char *program, char *mapdir)
 		}
 		if(setenv("XDG_RUNTIME_DIR", d->runtime, 1) < 0 ||
 		   setenv("XDG_CONFIG_HOME", d->config, 1) < 0 ||
-		   setenv("HOME", d->home, 1) < 0 || unsetenv("DISPLAY") < 0 ||
+		   setenv("HOME", d->home, 1) < 0 ||
+		   setenv("DISPLAY", "invalid", 1) < 0 ||
 		   unsetenv("DBUS_SESSION_BUS_ADDRESS") < 0 ||
 		   unsetenv("IBUS_ADDRESS") < 0){
 			dprintf(STDERR_FILENO, "set daemon environment: %s\n",