These are the forecast zones supported by the CERC API, which we will offer to the user on the forecast page.

We will use this library to make calls to the CERC API in our client.

To facilitate this, I have moved the sample forecast into the test fixtures, and added two new environment variables, CERC_API_HOST_URL and CERC_API_KEY.

We have agree that this method is rendering a single, three day forecast at a time, therefore it should be a show rather than an index method, and forecast should be singular in the path.

Users can now select a zone and fetch live data for that zone from the CERC API

This is so we can load styles more easily when debugging a
Capybara integration test which is saved to a local file
e.g. with `#save_and_open_page`.

This [mocking library][] will allow us to stub the HTTP response
from CERC which our `CercApiClient` receives.

We'll use it to set up scenarios for our integration tests.

[mocking library]:
https://github.com/bblimke/webmock

We have two scenarios:

1. "View air quality alerts": we see an alert with a
   different warning status for each of the 3 days included
   in the forecast

2. "See confirmation that there are current no air quality alert":
   We see that there are no alerts

We introduce three test helper modules:

1. a `Fixtures` module to build Forecasts for our tests

2. a `HttpStub` module to set WebMock stubs on HTTP traffic

3. an `AirQualitySteps` module to manage the implementation
   details for each "step" in the test. In our
   `view_air_quality_alerts_spec.rb` feature spec we
   ["include"][] this module in order to have access to its
   methods. This leaves the acceptance test
   clean and focused on describing the expected behaviour.

["include"]:
https://ruby-doc.org/docs/ruby-doc-bundle/ProgrammingRuby/book/classes.html#UC

Thanks to Prettier linter

One of our 2 acceptance tests now passes (albeit with a
naive implementation in the controller!)

```
scenario "See confirmation that there are current no air quality alert"
  given_an_air_pollution_prediction_for_today_w_low_status
  and_an_air_pollution_prediction_for_tomorrow_w_low_warning_status
  and_an_air_pollution_prediction_for_day_after_tomorrow_w_low_warning_status
  and_the_response_from_cercs_api_is_stubbed_accordingly

  when_i_look_at_the_forecasts
  then_i_see_that_there_are_no_current_air_quality_alerts
```

- stub environment variables
- use an inline JSON fixture for clarity

We implement a `ForecastSteps` module for our helper
methods.

Each row in the table now has a class describing the
information it carries:

- `air-pollution`
- `uv`
- `pollen`
- `temperature`

Each of the "value cells" now has a [`data-*` attribute][] of
`data-date` to identify which day's value it contains.

This will allow our integration tests to be clear and
maintainable.

[`data-*` attribute]:
https://developer.mozilla.org/en-US/docs/Learn/HTML/Howto/Use_data_attributes

I couldn't for now figure out how to resolve these warnings.
I tried updating all gems to their latest versions. There
isn't a more recent Ruby version to try.

Come back to this later, maybe.

```

air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/date_time_parser.rb:837: warning: statement not reached
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/date_time_parser.rb:691: warning: assigned but unused variable - testEof
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/address_lists_parser.rb:32457: warning: statement not reached
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/address_lists_parser.rb:32618: warning: statement not reached
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/address_lists_parser.rb:32654: warning: statement not reached
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/address_lists_parser.rb:32743: warning: statement not reached
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/address_lists_parser.rb:32759: warning: statement not reached
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/address_lists_parser.rb:32825: warning: statement not reached
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/address_lists_parser.rb:32866: warning: statement not reached
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/address_lists_parser.rb:32891: warning: statement not reached
air-text/vendor/bundle/ruby/3.3.0/gems/mail-2.8.1/lib/mail/parsers/address_lists_parser.rb:31987: warning: assigned but unused variable - testEof
air-text/vendor/bundle/ruby/3.3.0/gems/sassc-rails-2.1.2/lib/sassc/rails/functions.rb:7: warning: method redefined; discarding old asset_data_url
air-text/vendor/bundle/ruby/3.3.0/gems/sprockets-4.2.1/lib/sprockets/sass_processor.rb:274: warning: previous definition of asset_data_url was here
air-text/vendor/bundle/ruby/3.3.0/gems/sassc-rails-2.1.2/lib/sassc/rails/compressor.rb:7: warning: method redefined; discarding old initialize
air-text/vendor/bundle/ruby/3.3.0/gems/sprockets-4.2.1/lib/sprockets/sass_compressor.rb:39: warning: previous definition of initialize was here
air-text/vendor/bundle/ruby/3.3.0/gems/sassc-rails-2.1.2/lib/sassc/rails/compressor.rb:17: warning: method redefined; discarding old call
air-text/vendor/bundle/ruby/3.3.0/gems/sprockets-4.2.1/lib/sprockets/sass_compressor.rb:49: warning: previous definition of call was here
air-text/vendor/bundle/ruby/3.3.0/gems/lograge-0.14.0/lib/lograge/log_subscribers/base.rb:44: warning: method redefined; discarding old extract_status
air-text/vendor/bundle/ruby/3.3.0/gems/lograge-0.14.0/lib/lograge/log_subscribers/base.rb:41: warning: previous definition of extract_status was here
air-text/vendor/bundle/ruby/3.3.0/gems/lograge-0.14.0/lib/lograge.rb:82: warning: method redefined; discarding old ignore_tests
air-text/vendor/bundle/ruby/3.3.0/gems/lograge-0.14.0/lib/lograge.rb:28: warning: previous definition of ignore_tests was here
air-text/vendor/bundle/ruby/3.3.0/gems/lograge-0.14.0/lib/lograge.rb:82: warning: method redefined; discarding old ignore_tests
air-text/vendor/bundle/ruby/3.3.0/gems/lograge-0.14.0/lib/lograge.rb:28: warning: previous definition of ignore_tests was here
```

We take a representation of a Forecast from CERC's API and
build a list of our own Forecast entities.

For now our ForecastBuilder only uses the first zone
returned (i.e. only handles the scenario where we've asked
CERC's API for information on a particular zone). We will
likely develop this to handle all zones: that's what's
returned if we don't request a specific zone e.g.

```
curl "https://cerc.example.com/getforecast/all?numdays=3
```

For now we also leave out the rain and wind information as
we aren't sure how/if/where this is needed.

`Forecast#inspect` will return a string representation like:

```
"#<Forecast
  @obtained_at=2024-10-02 15:38:00 +0100
  @forecast_for=2024-10-02
  @zone=#<ForecastZone
    @id=29
    @name=Southwark
    @type=1>
  @air_pollution=#<AirPollutionPrediction
    @forecasted_at=2024-10-02 15:50:00 +0100
    @nitrogen_dioxide=1>
    @particulate_matter_10=1
    @particulate_matter_2_5=1
    @ozone=2
    @overall_score=2
    @overall_label=LOW>
  @UV=2
  @pollen=-999
  @temperature=#<TemperaturePrediction
    @min=10.0
    @max=16.6>>
```

We are going to build test fixtures for our own `Forecast`
entities as distinct from the JSON representations which we
receive from CERC's `/getforecast/all?` endpoint.

We will implement these alerts properly in coming commits.

We need a way to build our `Forecast` domain entities (and
their `AirPollutionPrediction`, `TemperaturePrediction`,
`ForecastZone` component entities).

We use [FactoryBot][] to help.

[FactoryBot]:
https://github.com/thoughtbot/factory_bot

The DAQI scale is from 1 to 10:

  1-3 = Low
  4-6 = Moderate
  7-9 = High
  10 = Very high