forecast.solar: use cached data after network failures

src/batcontrol/forecastsolar/fcsolar.py

@@ -113,7 +113,12 @@ def get_raw_data_from_provider(self, pvinstallation_name) -> dict:
         logger.info(
             'Requesting Information for PV Installation %s', name)
 
-        response = requests.get(url, timeout=60)
+        try:
+            response = requests.get(url, timeout=60)
+        except requests.exceptions.RequestException:
+            raise ProviderError(
+                'Forecast solar API request failed'
+            ) from None
         if response.status_code == 200:
             return json.loads(response.text)
         elif response.status_code == 429:

tests/batcontrol/forecastsolar/test_fcsolar.py

@@ -0,0 +1,60 @@
+"""Tests for the forecast.solar provider."""
+
+import traceback
+
+import pytest
+import pytz
+import requests
+
+from batcontrol.forecastsolar.baseclass import ProviderError
+from batcontrol.forecastsolar.fcsolar import FCSolar
+
+
+@pytest.fixture
+def instance():
+    """Create a forecast.solar provider with one PV installation."""
+    return FCSolar(
+        [{
+            'name': 'roof',
+            'lat': 52.17,
+            'lon': 21.25,
+            'declination': 30,
+            'azimuth': 34,
+            'kWp': 10.0,
+        }],
+        pytz.timezone('Europe/Warsaw'),
+        min_time_between_api_calls=900,
+    )
+
+
+def test_request_error_is_wrapped_without_sensitive_details(instance, mocker):
+    """ProviderError must not expose an API key from the request URL."""
+    mocker.patch(
+        'batcontrol.forecastsolar.fcsolar.requests.get',
+        side_effect=requests.exceptions.ConnectionError(
+            'request failed for https://api.forecast.solar/secret-key/estimate'),
+    )
+
+    with pytest.raises(ProviderError) as error_info:
+        instance.get_raw_data_from_provider('roof')
+
+    assert str(error_info.value) == 'Forecast solar API request failed'
+    formatted_error = ''.join(traceback.format_exception(
+        type(error_info.value), error_info.value, error_info.value.__traceback__))
+    assert 'secret-key' not in formatted_error
+
+
+def test_refresh_keeps_cached_data_on_request_error(instance, mocker, caplog):
+    """A transient request failure must leave the last good response cached."""
+    cached_response = {'result': 'last-known-good'}
+    instance.store_raw_data('roof', cached_response)
+    mocker.patch(
+        'batcontrol.forecastsolar.fcsolar.requests.get',
+        side_effect=requests.exceptions.ConnectionError(
+            'request failed for https://api.forecast.solar/secret-key/estimate'),
+    )
+
+    instance.refresh_data()
+
+    assert instance.get_raw_data('roof') == cached_response
+    assert 'secret-key' not in caplog.text