Make test failure messages more verbose (and thus useful to testing operators).

client/site_tests/factory_Keyboard/factory_Keyboard.py

 # -*- coding: utf-8 -*-
 #
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 
 # DESCRIPTION :
 #
 # Intended for use during manufacturing to validate that all keyboard
@@ skipping 115 matching lines @@
 
 class factory_Keyboard(test.test):
     version = 1
     preserve_srcdir = True
 
     def run_once(self, layout=None):
 
         factory.log('%s run_once' % self.__class__)
 
         os.chdir(self.srcdir)
-        kbd_image = cairo.ImageSurface.create_from_png('%s.png' % layout)
-        image_size = (kbd_image.get_width(), kbd_image.get_height())
 
-        with open('%s.bindings' % layout, 'r') as file:
-            bindings = eval(file.read())
+        try:
+            kbd_image = cairo.ImageSurface.create_from_png('%s.png' % layout)
+            image_size = (kbd_image.get_width(), kbd_image.get_height())
+        except cairo.Error as e:
+            raise error.TestNAError('Error while opening %s.png: %s' %
+                                    (layout, e.message))
+
+        try:
+            with open('%s.bindings' % layout, 'r') as file:
+                bindings = eval(file.read())
+        except IOError as e:
+            raise error.TestNAError('Error while opening %s: %s [Errno %d]' %
+                                    (e.filename, e.strerror, e.errno))
 
         test = KeyboardTest(kbd_image, bindings)
 
         drawing_area = gtk.DrawingArea()
         drawing_area.set_size_request(*image_size)
         drawing_area.connect('expose_event', test.expose_event)
         drawing_area.add_events(gdk.EXPOSURE_MASK)
 
         countdown_widget, countdown_label = ful.make_countdown_widget()
         gobject.timeout_add(1000, test.timer_event, countdown_label)
 
         test_widget = gtk.VBox()
         test_widget.set_spacing(20)
         test_widget.pack_start(drawing_area, False, False)
         test_widget.pack_start(countdown_widget, False, False)
 
         ful.run_test_widget(self.job, test_widget,
             window_registration_callback=test.register_callbacks)
 
         missing = test.calc_missing_string()
         if missing:
             raise error.TestFail(missing)
 
         factory.log('%s run_once finished' % self.__class__)