Add tests for Plugwise integration

[CoMPaTech]

Proposed change

Add testing fixtures and tests (besides the mandatory config_flow for the Plugwise integration. Earlier I prepared a version with aiohttp mocking, but that would generate a hefty amount of XML data in fixtures (even gzipped), rewrote using pickles written out by our API module from that same data.

I'm trying to keep the amount of fixtures as low as possible - I could tidy up a bit more by using a smaller environment, though the selected three environments to run the tests against are about the most diverse we have test data available for from our API module development.

Comments or recommendations welcome (here or on discord)

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue: Update plugwise to async and config_flow  #33691 Update plugwise to async and config_flow sensor part #36219
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the [development checklist][dev-checklist]
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

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

• Documentation added/updated for [www.home-assistant.io][docs-repository]

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

• The [manifest file][manifest-docs] has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following [Integration Quality Scale][quality-scale]:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

[probot-home-assistant]

Hey there @bouwew, mind taking a look at this pull request as its been labeled with a integration (plugwise) you are listed as a codeowner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[CoMPaTech]

Set to draft so #36378 can take presedence and we can beef up this one with binary_sensors and switch tests.

[CoMPaTech]

Not sure why codecov is complaining (in more detail, it's complaining on coverage differences outside my changes).

Local coverage report shows:

collecting ...
 tests/components/plugwise/test_binary_sensor.py ✓✓                                                                                                                                                                             11% █▏
 tests/components/plugwise/test_climate.py ✓✓✓✓                                                                                                                                                                                 32% ███▎
 tests/components/plugwise/test_config_flow.py ✓✓✓                                                                                                                                                                              47% ████▊
 tests/components/plugwise/test_init.py ✓✓✓✓✓                                                                                                                                                                                   74% ███████▍
 tests/components/plugwise/test_sensor.py ✓✓✓                                                                                                                                                                                   89% ████████▉
 tests/components/plugwise/test_switch.py ✓✓                                                                                                                                                                                   100% ██████████

---------- coverage: platform darwin, python 3.7.3-final-0 -----------
Name                                                 Stmts   Miss  Cover   Missing
----------------------------------------------------------------------------------
homeassistant/components/plugwise/__init__.py           99      6    94%   63, 108, 120-131
homeassistant/components/plugwise/binary_sensor.py      55     11    80%   68, 81-83, 86-87, 97-101
homeassistant/components/plugwise/climate.py           165     24    85%   106, 108, 110-113, 142, 159, 191-194, 200-205, 212-213, 222-223, 263-265
homeassistant/components/plugwise/config_flow.py        42      6    86%   61-63, 66-69
homeassistant/components/plugwise/const.py              29      0   100%
homeassistant/components/plugwise/sensor.py            128     34    73%   209-222, 284-286, 304-308, 313, 318-339, 365-367
homeassistant/components/plugwise/switch.py             49      7    86%   57-58, 66-67, 77-79
----------------------------------------------------------------------------------
TOTAL                                                  567     88    84%

[CoMPaTech]

Low score on sensor.py is largely affecting all of them (Question: how to trigger a DataUpdateCoordinator callback through testing?)

[bouwew]

Ok, as fellow code-owner

[CoMPaTech]

If someone is open for discussion on xml versus pickle, please ping me on discord (or mention me in the appropriate dev-channel).

[CoMPaTech]

Updated pickles according to newer release of the module (on PyPi). The improved testing of config_flow (which were oversighted in #37289 and are PRed for fix in #37229) still need to be rebased.

[CoMPaTech]

@MartinHjelmare just re-checked myself (using the famous websearch) and looks like https://pypi.org/project/jsonpickle/ does provide a solution for storing sets and 'it works on my laptop'. I'm not sure how to get (if allowed anyway) the jsonpickle module in onto testing (reading https://developers.home-assistant.io/docs/development_testing points towards a list in the script, but I'm not clear which list/dict is for testing only).

[CoMPaTech]

(jsonpickle as a module worked out of the box?)

[MartinHjelmare]

Add it to the integration manifest requirements.

[CoMPaTech]

Add it to the integration manifest requirements.

Too bad we cant select for testing purposes only, not in the least since we have to pin requirements :(

[MartinHjelmare]

We don't have any infrastructure for integration specific test dependencies. Then we would need to add it to our common test requirements. I can check if we want that.

[MartinHjelmare]

We have a go ahead to add jsonpickle to our common test requirements. Please add it to requirements_test.txt, sorted 🔡.

[MartinHjelmare]

Great!

[CoMPaTech]

Having these in place will ensure the code is better and other people will be able to modify/extend with more ease and security :)