Add offset option to sensor.gtfs

[Kernald]

Description:

The rationale behind this addition is this: if you have a 10 minutes walk to your bus stop, you're not interested in knowing the next bus is in 4 minutes. Instead, you're interested in knowing that the next one is in 12 minutes, so you'd better go and catch it.
The offset option is meant to do this: add a duration, and all departures before this duration will be ignored.

Note that I know this PR isn't ready for merge. It's my first PR in here, and I never wrote Python before, things are probably wrong. I'm not so sure about the name offset, for a start. I'll update the documentation once everything else is fixed in this PR.

Pull request in home-assistant.github.io with documentation (if applicable): home-assistant/home-assistant.io#2883

Example entry for configuration.yaml (if applicable):

- platform: gtfs
  name: tisseo_home_af
  origin: !secret tisseo_stop_home
  destination: !secret tisseo_stop_af_arrival
  offset:
    minutes: 16
  data: tisseo_gtfs.zip

Checklist:

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.github.io

If the code communicates with devices, web services, or third-party tools:

• Local tests with tox run successfully. Your PR cannot be merged unless tests pass
• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.

If the code does not interact with devices:

• Local tests with tox run successfully. Your PR cannot be merged unless tests pass
• Tests have been added to verify that the new code works.

[houndci-bot]

line too long (82 > 79 characters)

[Kernald]

About that, should I import datetime.timedelta at the top of the file, or go ahead and split this line?

[balloob]

Add an enter after :

[Kernald]

Like I said, it's the first time I ever wrote Python. I'm not sure what's @property meant for. I expected the offset to show up in the sensor attributes (on the web UI), but it doesn't. Is this property mandatory?

[fabaff]

Use device_state_attributes() to collect and present attributes in the frontend.

[balloob]

This component actually already implements device_state_attributes, which returns self._attributes. self._attributes is updated inside update, so just make sure you set the attribute there.

[balloob]

That being said, we can also just remove it. Maybe not so important to have it in the attributes?

[Kernald]

Having it in the attributes might be useful for some notifications or that kind of things. I'll fix this, thanks for the pointers!

[balloob]

Looks good. Ok to merge when line length issue addressed and property either added to self._attributes or removed.

[homeassistant]

Hi @Kernald,

It seems you haven't yet signed a CLA. Please do so here.

Once you do that we will be able to review and accept this pull request.

Thanks!

[houndci-bot]

continuation line unaligned for hanging indent

[fabaff]

All comments addressed.