When querying values from Setting, return None if key does not exists. Fixes bug 1387278

Fixes: https://launchpad.net/bugs/1387278

openlp/core/common/settings.py

@@ -431,10 +431,14 @@ class Settings(QtCore.QSettings):
         :param key: The key to return the value from.
         """
         # if group() is not empty the group has not been specified together with the key.
-        if self.group():
-            default_value = Settings.__default_settings__[self.group() + '/' + key]
-        else:
-            default_value = Settings.__default_settings__[key]
+        try:
+            if self.group():
+                default_value = Settings.__default_settings__[self.group() + '/' + key]
+            else:
+                default_value = Settings.__default_settings__[key]
+        except KeyError:
+            log.warning('Key "%s" was not found in settings, returning None!' % key)
+            return None
         setting = super(Settings, self).value(key, default_value)
         return self._convert_value(setting, default_value)
 

tests/functional/openlp_core_common/test_settings.py

@@ -115,3 +115,15 @@ class TestSettings(TestCase, TestMixin):
 
         # THEN the new value is returned when re-read
         self.assertEqual('very short', Settings().value('test/extend'), 'The saved value should be returned')
+
+    def settings_nonexisting_test(self):
+        """
+        Test the Settings on query for non-existing value
+        """
+        # GIVEN: A new Settings setup
+
+        # WHEN reading a setting that doesn't exists
+        does_not_exist_value = Settings().value('core/does not exists')
+
+        # THEN None should be returned
+        self.assertEqual(does_not_exist_value, None, 'The value should be None')