start_date now supported in schedules

start_date defines when a meeting series begins.  start_date
is used in lieu of the current date when rebuilding the calendar.

This will ultimately let us move away from needing to have
biweekly-odd and biweekly-even.

I also added an example.yaml with a start_date

Change-Id: I0c5f6e5951b6c15b949f599182f48aa132b76abb

README.rst

@@ -122,6 +122,8 @@ Each meeting consists of:
 
   * ``time``: time string in UTC [MANDATORY]
   * ``duration``: duration of the meeting in minutes; defaults to 60
+  * ``start_date``: the date the first meeting takes place on or after.
+      Format `YYYYMMDD`, all values must be zero-padded.
   * ``day``: the day of week the meeting takes place [MANDATORY]
   * ``irc``: the irc room in which the meeting is held [MANDATORY]
   * ``frequency``: frequent occurrence of the meeting [MANDATORY]

meetings/example2.yaml

@@ -0,0 +1,13 @@
+project: Example Start Date Team Meeting
+agenda_url: http://agenda.com/
+project_url: http://project.com
+schedule:
+  - time: '1600'
+    duration: 45
+    start_date: 20150801
+    day: Thursday
+    irc: openstack-meeting
+    frequency: weekly
+chair: John Doe
+description:  >
+  If you're interested in Example, we have a 45 minute long weekly meeting for you to attend.

yaml2ical/ical.py

@@ -63,8 +63,8 @@ class Yaml2IcalCalendar(icalendar.Calendar):
             event.add('description', ical_descript)
 
             # get starting date
-            start_date = datetime.datetime.utcnow()
-            next_meeting = sch.recurrence.next_occurence(start_date, sch.day)
+            next_meeting = sch.recurrence.next_occurence(sch.start_date,
+                                                         sch.day)
             next_meeting_date = datetime.datetime(next_meeting.year,
                                                   next_meeting.month,
                                                   next_meeting.day,

yaml2ical/meeting.py

@@ -53,6 +53,17 @@ class Schedule(object):
                   "attribute '{0}'".format(e.args[0]))
             raise
 
+        # optional: start_date defaults to the current date if not present
+        if 'start_date' in sched_yaml:
+            try:
+                self.start_date = datetime.datetime.strptime(
+                    str(sched_yaml['start_date']), '%Y%m%d')
+            except ValueError:
+                raise ValueError("Could not parse 'start_date' (%s) in %s" %
+                                (sched_yaml['start_date'], self.filefrom))
+        else:
+            self.start_date = datetime.datetime.utcnow()
+
         # optional: duration
         if 'duration' in sched_yaml:
             try:

yaml2ical/tests/sample_data.py

@@ -176,3 +176,19 @@ description: >
 agenda: |
   * Debate whether this should be a longer meeting
 """
+
+MEETING_WITH_START_DATE = """
+project: OpenStack Subteam 8 Meeting
+schedule:
+  - time: '1200'
+    duration: 30
+    day: Thursday
+    start_date: 20150801
+    irc: openstack-meeting
+    frequency: weekly
+chair: Shannon Stacker
+description: >
+    Weekly short meeting for Subteam project.
+agenda: |
+  * Debate whether this should be a longer meeting
+"""

yaml2ical/tests/test_meeting_recurrence.py

@@ -0,0 +1,28 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import datetime
+import unittest
+
+from yaml2ical import meeting
+from yaml2ical import recurrence
+from yaml2ical.tests import sample_data
+
+
+class Meeting_RecurrenceTestCase(unittest.TestCase):
+
+    def test_next_meeting_start_date(self):
+        m = meeting.load_meetings(sample_data.MEETING_WITH_START_DATE)[0]
+        self.assertEqual(
+            datetime.datetime(2015, 8, 6, 0, 0),
+            recurrence.WeeklyRecurrence().next_occurence(
+                m.schedules[0].start_date, m.schedules[0].day))