diff --git a/tests/functional/openlp_core_ui/test_mainwindow.py b/tests/functional/openlp_core_ui/test_mainwindow.py
new file mode 100644
index 000000000..0b17828b9
--- /dev/null
+++ b/tests/functional/openlp_core_ui/test_mainwindow.py
@@ -0,0 +1,97 @@
+# -*- coding: utf-8 -*-
+# vim: autoindent shiftwidth=4 expandtab textwidth=120 tabstop=4 softtabstop=4
+
+###############################################################################
+# OpenLP - Open Source Lyrics Projection                                      #
+# --------------------------------------------------------------------------- #
+# Copyright (c) 2008-2014 Raoul Snyman                                        #
+# Portions copyright (c) 2008-2014 Tim Bentley, Gerald Britton, Jonathan      #
+# Corwin, Samuel Findlay, Michael Gorven, Scott Guerrieri, Matthias Hub,      #
+# Meinert Jordan, Armin Köhler, Erik Lundin, Edwin Lunando, Brian T. Meyer.   #
+# Joshua Miller, Stevan Pettit, Andreas Preikschat, Mattias Põldaru,          #
+# Christian Richter, Philip Ridout, Simon Scudder, Jeffrey Smith,             #
+# Maikel Stuivenberg, Martin Thompson, Jon Tibble, Dave Warnock,              #
+# Frode Woldsund, Martin Zibricky, Patrick Zimmermann                         #
+# --------------------------------------------------------------------------- #
+# This program is free software; you can redistribute it and/or modify it     #
+# under the terms of the GNU General Public License as published by the Free  #
+# Software Foundation; version 2 of the License.                              #
+#                                                                             #
+# This program is distributed in the hope that it will be useful, but WITHOUT #
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or       #
+# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for    #
+# more details.                                                               #
+#                                                                             #
+# You should have received a copy of the GNU General Public License along     #
+# with this program; if not, write to the Free Software Foundation, Inc., 59  #
+# Temple Place, Suite 330, Boston, MA 02111-1307 USA                          #
+###############################################################################
+"""
+Package to test openlp.core.ui.mainwindow package.
+"""
+import os
+
+from unittest import TestCase
+
+from openlp.core.ui.mainwindow import MainWindow
+from openlp.core.common.registry import Registry
+from tests.utils.constants import TEST_RESOURCES_PATH
+from tests.helpers.testmixin import TestMixin
+from tests.functional import MagicMock, patch
+
+
+class TestMainWindow(TestCase, TestMixin):
+
+    def setUp(self):
+        Registry.create()
+        self.registry = Registry()
+        self.get_application()
+        # Mock cursor busy/normal methods.
+        self.app.set_busy_cursor = MagicMock()
+        self.app.set_normal_cursor = MagicMock()
+        self.app.args = []
+        Registry().register('application', self.app)
+        # Mock classes and methods used by mainwindow.
+        with patch('openlp.core.ui.mainwindow.SettingsForm') as mocked_settings_form, \
+                patch('openlp.core.ui.mainwindow.ImageManager') as mocked_image_manager, \
+                patch('openlp.core.ui.mainwindow.LiveController') as mocked_live_controller, \
+                patch('openlp.core.ui.mainwindow.PreviewController') as mocked_preview_controller, \
+                patch('openlp.core.ui.mainwindow.OpenLPDockWidget') as mocked_dock_widget, \
+                patch('openlp.core.ui.mainwindow.QtGui.QToolBox') as mocked_q_tool_box_class, \
+                patch('openlp.core.ui.mainwindow.QtGui.QMainWindow.addDockWidget') as mocked_add_dock_method, \
+                patch('openlp.core.ui.mainwindow.ThemeManager') as mocked_theme_manager, \
+                patch('openlp.core.ui.mainwindow.Renderer') as mocked_renderer:
+            self.main_window = MainWindow()
+
+    def tearDown(self):
+        del self.main_window
+
+    def cmd_line_file_test(self):
+        """
+        Test that passing a service file from the command line loads the service.
+        """
+        # GIVEN a service as an argument to openlp
+        service = os.path.join(TEST_RESOURCES_PATH, 'service', 'test.osz')
+        self.main_window.arguments = [service]
+        with patch('openlp.core.ui.servicemanager.ServiceManager.load_file') as mocked_load_path:
+
+            # WHEN the argument is processed
+            self.main_window.open_cmd_line_files()
+
+            # THEN the service from the arguments is loaded
+            mocked_load_path.assert_called_with(service), 'load_path should have been called with the service\'s path'
+
+    def cmd_line_arg_test(self):
+        """
+        Test that passing a non service file does nothing.
+        """
+        # GIVEN a non service file as an argument to openlp
+        service = os.path.join('openlp.py')
+        self.main_window.arguments = [service]
+        with patch('openlp.core.ui.servicemanager.ServiceManager.load_file') as mocked_load_path:
+
+            # WHEN the argument is processed
+            self.main_window.open_cmd_line_files()
+
+            # THEN the file should not be opened
+            assert not mocked_load_path.called, 'load_path should not have been called'
diff --git a/tests/resources/service/test.osz b/tests/resources/service/test.osz
new file mode 100644
index 000000000..a289c0775
Binary files /dev/null and b/tests/resources/service/test.osz differ