Fix unit tests

Author: cderici

juju/model.py

@@ -2749,7 +2749,7 @@ def _raise_for_status(entities, status):
             if not busy:
                 break
             busy = "\n  ".join(busy)
-            if timeout and datetime.now() - start_time > timeout:
+            if timeout is not None and datetime.now() - start_time > timeout:
                 raise jasyncio.TimeoutError("Timed out waiting for model:\n" + busy)
             if last_log_time is None or datetime.now() - last_log_time > log_interval:
                 log.info("Waiting for model:\n  " + busy)

tests/unit/test_model.py

@@ -397,7 +397,7 @@ async def test_wait_for_active_units_waiting_for_units(self):
             mock_apps.return_value = apps
             m = Model()
 
-            await m.wait_for_idle(apps=["dummy_app"], status="active", wait_for_units=1,
+            await m.wait_for_idle(apps=["dummy_app"], status="active", wait_for_at_least_units=1,
                                   timeout=None)
 
         mock_apps.assert_called_with()