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Contribute to Workalendar

Use it (and test it)

If you are using workalendar, you are already contributing to it. As long as you are able to check its result, compare the designated working days and holidays to the reality, and make sure these are right, you're helping.

If any of the computed holidays for the country / area your are using is wrong, please report it using the Github issues.

Report an issue

If you think you've found a bug you can report an issue. In order to help us sort this out, please follow the guidelines:

  • Tell us which workalendar version (master, PyPI release) you are using.
  • Tell us which Python version you are using, and your platform.
  • Give us extensive details on the country / area Calendar, the exact date(s) that was (were) computed and the one(s) that should have been the correct result.
  • If possible, please provide us a reliable source about the designated country / area calendar, where we could effectively check that we were wrong about a date, and giving us a way to patch our code properly so we can fix the bug.

Adding new calendars

Since workalendar is mainly built around configuration variables and generic methods, it's not that difficult to add a calendar to our codebase. A few mandatory steps should be observed:

  1. Fork the repository and create a new branch named after the calendar you want to implement,
  2. Add a test class to the workalendar test suite that checks holidays,
  3. Implement the class using the core class APIs as much as possible. Test it until all tests pass.
  4. Make a nice pull-request we'll be glad to review and merge when it's perfect.

Please respect the PEP8 convention, otherwise your PR won't be accepted.

Example

Let's assume you want to include the holidays of the magic (fictional) kingdom of "Zhraa", which has a few holidays of different kind.

For the sake of the example, it has the following specs:

  • it's a Gregorian-based Calendar (i.e. Western Europe / America),
  • even if the King is not versed into religions, the kingdom includes a few Christian holidays,
  • even if you never knew about it, it is set in Europe,

Here is a list of the holidays in Zhraa:

  • January 1st, New year's Day,
  • May 1st, Labour day,
  • Easter Monday, which is variable (from March to May),
  • The first monday in June, to celebrate the birth of the Founder of the Kingdom, Zhraa (nobody knows the exact day he was born, so this day was chosen as a convention),
  • The birthday of the King, August 2nd.
  • Christmas Day, Dec 25th.

Getting ready

You'll need to install workalendar dependencies beforehand. What's great is that you'll use virtualenv to set it up. Or even better: virtualenvwrapper. Just go in your working copy (cloned from github) of workalendar and type, for example:

mkvirtualenv WORKALENDAR
pip install -e ./

Test-driven start

Let's prepare the Zhraa class. Edit the workalendar/europe/zhraa.py file and add a class like this:

from workalendar.core import WesternCalendar

class Zhraa(WesternCalendar):
    "Kingdom of Zhraa"

The docstring is not mandatory, but if you omit it, the name property of your class will be the name of your class. For example, using upper CamelCase, KingdomOfZhraa. For a more human-readable label, use your docstring.

Meanwhile, in the workalendar/europe/__init__.py file, add these snippets where needed:

from .zhraa import Zhraa
# ...
__all__ = (
    'Belgium',
    'CzechRepublic',
    # ...
    'Zhraa',
)

Now, we're building a test class. Edit the workalendar/tests/test_europe.py file and add the following code:

from workalendar.europe import Zhraa
# snip...

class ZhraaTest(GenericCalendarTest):
    cal_class = Zhraa

    def test_year_2014(self):
        holidays = self.cal.holidays_set(2014)
        self.assertIn(date(2014, 1, 1), holidays)  # new year
        self.assertIn(date(2014, 5, 1), holidays)  # labour day
        self.assertIn(date(2014, 8, 2), holidays)  # king birthday
        self.assertIn(date(2014, 12, 25), holidays)  # Xmas
        # variable days
        self.assertIn(date(2014, 4, 21), holidays)  # easter monday
        self.assertIn(date(2014, 6, 2), holidays)  # First MON in June

of course, if you run the test using the tox or py.test command, this will fail, since we haven't implemented anything yet.

Install tox using the following command:

workon WORKALENDAR
pip install tox

With the WesternCalendar base class you have at least one holiday as a bonus: the New year's day, which is commonly a holiday.

Add fixed days

class Zhraa(WesternCalendar):
    FIXED_HOLIDAYS = WesternCalendar.FIXED_HOLIDAYS + (
        (5, 1, "Labour Day"),
        (8, 2, "King Birthday"),
    )

Now we've got 3 holidays out of 6.

Add religious holidays

Using ChristianMixin as a base to our Zhraa class will instantly add Christmas Day as a holiday. Now we can add Easter monday just by switching the correct flag.

from workalendar.core import WesternCalendar, ChristianMixin

class Zhraa(WesternCalendar, ChristianMixin):
    include_easter_monday = True
    FIXED_HOLIDAYS = WesternCalendar.FIXED_HOLIDAYS + (
        (5, 1, "Labour Day"),
        (8, 2, "King Birthday"),
    )

Almost there, 5 holidays out of 6.

Add variable "non-usual" holidays

There are many static methods that will grant you a clean access to variable days computation. It's very easy to add days like the "Birthday of the Founder":

class Zhraa(WesternCalendar, ChristianMixin):
    include_easter_monday = True
    FIXED_HOLIDAYS = WesternCalendar.FIXED_HOLIDAYS + (
        (5, 1, "Labour Day"),
        (8, 2, "King Birthday"),
    )

    def get_variable_days(self, year):
        # usual variable days
        days = super(Zhraa, self).get_variable_days(year)

        days.append(
            (Zhraa.get_nth_weekday_in_month(year, 6, MON),
            'Day of the Founder'),
        )
        return days

Please mind that the returned days is a list of tuples. The first item being a date object (in the Python datetime.date sense) and the second one is the label string.

Add you calendar to the global registry

If you're adding a Country calendar that has an ISO code, you may want to add it to our global registry.

Workalendar is providing a registry that you can use to query and fetch calendar based on their ISO code. For the current example, let's pretend that the Zhraa Kingdom ISO code is ZK.

To register, add the following:

from ..registry_tools import iso_register

@iso_register('ZK')
class Zhraa(WesternCalendar, ChristianMixin):
    # The rest of your code...

You're done for the code!

There you are. Commit with a nice commit message, test, make sure it works for the other years as well - there might be exceptions to the common rules - and you're almost there.

The final steps

Do not forget to:

  1. put the appropriate doctring in the Calendar class.
  2. add your calendar in the README.rst file, included in the appropriate continent.
  3. add your calendar to the Changelog.md file.

Note Please, do NOT change the version number in the changelog or in the setup.py file. It's the project maintainers' duty to decide when to release and how to increment the version number, according to the impact of the changes.

We're planning to build a complete documentation for the other cases (special holiday rules, other calendar types, other religions, etc). But with this tutorial you're sorted for a lot of other calendars.

Other code contributions

There are dozens of calendars all over the world. We'd appreciate you to contribute to the core of the library by adding some new Mixins or Calendars.

Bear in mind that the code you'd provide must be tested using unittests before you submit your pull-request.