Fix initialisation of song usage dates

Fixes: https://launchpad.net/bugs/1661416

openlp/plugins/songusage/forms/songusagedetailform.py

@@ -22,6 +22,7 @@
 
 import logging
 import os
+from datetime import datetime
 
 from PyQt5 import QtCore, QtWidgets
 from sqlalchemy.sql import and_
@@ -52,8 +53,16 @@ class SongUsageDetailForm(QtWidgets.QDialog, Ui_SongUsageDetailDialog, RegistryP
         """
         We need to set up the screen
         """
-        self.from_date_calendar.setSelectedDate(Settings().value(self.plugin.settings_section + '/from date'))
-        self.to_date_calendar.setSelectedDate(Settings().value(self.plugin.settings_section + '/to date'))
+        from_date = Settings().value(self.plugin.settings_section + '/from date')
+        if from_date:
+            self.from_date_calendar.setSelectedDate(from_date)
+        else:
+            self.from_date_calendar.setSelectedDate(datetime.today().replace(day=1))
+        to_date = Settings().value(self.plugin.settings_section + '/to date')
+        if to_date:
+            self.to_date_calendar.setSelectedDate(to_date)
+        else:
+            self.to_date_calendar.setSelectedDate(datetime.today())
         self.file_line_edit.setText(Settings().value(self.plugin.settings_section + '/last directory export'))
 
     def define_output_location(self):

tests/interfaces/openlp_plugins/songusage/test_songusagedetailform.py

@@ -0,0 +1,99 @@
+# -*- coding: utf-8 -*-
+# vim: autoindent shiftwidth=4 expandtab textwidth=120 tabstop=4 softtabstop=4
+
+###############################################################################
+# OpenLP - Open Source Lyrics Projection                                      #
+# --------------------------------------------------------------------------- #
+# Copyright (c) 2008-2017 OpenLP Developers                                   #
+# --------------------------------------------------------------------------- #
+# 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 the openlp.plugins.songusage.forms.songusagedetailform package.
+"""
+from unittest import TestCase
+from unittest.mock import MagicMock, patch
+
+from PyQt5 import QtCore, QtWidgets
+
+from openlp.core.common import Registry
+from openlp.plugins.songusage.forms.songusagedetailform import SongUsageDetailForm
+
+from tests.helpers.testmixin import TestMixin
+
+
+class TestSongUsageDetailForm(TestCase, TestMixin):
+    """
+    Test the SongUsageDetailForm class
+    """
+
+    def setUp(self):
+        """
+        Create the UI
+        """
+        Registry.create()
+        self.setup_application()
+        self.main_window = QtWidgets.QMainWindow()
+        self.mocked_plugin = MagicMock()
+        Registry().register('main_window', self.main_window)
+        self.form = SongUsageDetailForm(self.mocked_plugin, self.main_window)
+
+    def tearDown(self):
+        """
+        Delete all the C++ objects at the end so that we don't have a segfault
+        """
+        del self.form
+        del self.main_window
+
+    @patch('openlp.plugins.songusage.forms.songusagedetailform.Settings')
+    def test_initalise_without_settings(self, MockedSettings):
+        """
+        Test the initialise() method when there are no settings
+        """
+        # GIVEN: A song usage detail form and a mocked settings object
+        mocked_settings = MagicMock()
+        mocked_settings.value.side_effect = ['', None, '']
+        MockedSettings.return_value = mocked_settings
+
+        # WHEN: initialise() is called
+        self.form.initialise()
+
+        # THEN: The dates on the calendar should be this month
+        today = QtCore.QDate.currentDate()
+        month_start = QtCore.QDate.currentDate().addDays(1 - today.day())
+        assert self.form.from_date_calendar.selectedDate() == month_start, \
+            self.form.from_date_calendar.selectedDate()
+        assert self.form.to_date_calendar.selectedDate() == today, \
+            self.form.to_date_calendar.selectedDate()
+
+    @patch('openlp.plugins.songusage.forms.songusagedetailform.Settings')
+    def test_initalise_with_settings(self, MockedSettings):
+        """
+        Test the initialise() method when there are existing settings
+        """
+        # GIVEN: A song usage detail form and a mocked settings object
+        to_date = QtCore.QDate.currentDate().addDays(-1)
+        from_date = QtCore.QDate.currentDate().addDays(2 - to_date.day())
+        mocked_settings = MagicMock()
+        mocked_settings.value.side_effect = [from_date, to_date, '']
+        MockedSettings.return_value = mocked_settings
+
+        # WHEN: initialise() is called
+        self.form.initialise()
+
+        # THEN: The dates on the calendar should be this month
+        assert self.form.from_date_calendar.selectedDate() == from_date, \
+            self.form.from_date_calendar.selectedDate()
+        assert self.form.to_date_calendar.selectedDate() == to_date, \
+            self.form.to_date_calendar.selectedDate()