panic notifier: display default value if not set

If we didn't set values for @type and @iobase in
XML, libvirt will use the default value.
Currently, virt-manager will display "-" if we don't
set any values.
This patch will use default value for display.
And update test case to cover this scenario.

Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>

tests/xmlparse.py

@@ -787,8 +787,8 @@ class XMLParseTest(unittest.TestCase):
         dev1 = guest.get_devices("panic")[0]
 
         check = self._make_checker(dev1)
-        check("type", "isa", "isa")
-        check("iobase", "0x505", "0x506")
+        check("type", "isa", None, "isa")
+        check("iobase", "0x505", None, "0x506")
         self._alter_compare(guest.get_xml_config(), outfile)
 
     def testAddRemoveDevices(self):

virtManager/details.py

@@ -3110,6 +3110,9 @@ class vmmDetails(vmmGObjectUI):
             widgetname = "panic-" + param.replace("_", "-")
             if not val:
                 val = getattr(dev, param)
+                if not val:
+                    propername = param.upper() + "_DEFAULT"
+                    val = getattr(virtinst.VirtualPanicDevice, propername, "-").upper()
 
             uihelpers.set_grid_row_visible(self.widget(widgetname), True)
             self.widget(widgetname).set_text(val or "-")

virtinst/devicepanic.py

@@ -26,6 +26,7 @@ class VirtualPanicDevice(VirtualDevice):
 
     virtual_device_type = VirtualDevice.VIRTUAL_DEV_PANIC
     ADDRESS_TYPE_ISA = "isa"
+    TYPE_DEFAULT = ADDRESS_TYPE_ISA
     TYPES = [ADDRESS_TYPE_ISA]
     IOBASE_DEFAULT = "0x505"