use virtual_machine_by_boards

unittests/test_json_machine.py

@@ -60,12 +60,14 @@ def test_exceptions(self):
         self.assertEqual(vchip33.tag_ids, chip33.tag_ids)
 
     def test_monitor_exceptions(self):
-        vm = virtual_machine(width=8, height=8)
+        vm = virtual_machine_by_boards(1)
         MachineDataWriter.mock().set_machine(vm)
-        chip02 = vm[0, 2]
+        for chip in vm.chips:
+            if chip.ip_address is None:
+                break
         # Hack in an extra monitor
-        chip02._scamp_processors = tuple([0, 1])
-        chip02._placable_processors = tuple([2, 3, 4, 5, 6, 7, 8, 9])
+        chip._scamp_processors = tuple([0, 1])
+        chip._placable_processors = tuple([2, 3, 4, 5, 6, 7, 8, 9])
         jpath = mktemp("json")
         # Should still be able to write json even with more than one monitor
         to_json_path(jpath)