Made ValueExceptions more explicit in the ScreenGeometry class.

(bzr r2178.1.1)

1 files changed, 11 insertions, 2 deletions

diff --git a/tests/autopilot/autopilot/emulators/X11.py b/tests/autopilot/autopilot/emulators/X11.py
index 1360198d4..cbc5a1605 100644
--- a/tests/autopilot/autopilot/emulators/X11.py
+++ b/tests/autopilot/autopilot/emulators/X11.py
@@ -333,10 +333,19 @@ class ScreenGeometry:
 return self._default_screen.get_primary_monitor()
 
 def set_primary_monitor(self, monitor):
+ """Set `monitor` to be the primary monitor.
+
+ `monitor` must be an integer between 0 and the number of configured monitors.
+ ValueError is raised if an invalid monitor is specified.
+
+ """
+ if monitor < 0 or monitor >= self.get_num_monitors():
+ raise ValueError('Monitor %d is not in valid range of 0 <= monitor < %d.' % (self.get_num_monitors()))
+
 monitor_name = self._default_screen.get_monitor_plug_name(monitor)
 
- if not monitor_name or len(monitor_name) == 0:
- raise ValueError('Invalid monitor found')
+ if not monitor_name:
+ raise ValueError('Could not get monitor name from monitor number.')
 
 glxinfo_out = subprocess.check_output("glxinfo")
 for dri in self._blacklisted_drivers: