feat(automatic-exchange-rate): track unsuccessful runs

app/apps/currencies/tests/__init__.py

@@ -0,0 +1 @@
+# Tests package for currencies app

app/apps/currencies/tests/test_automatic_exchange_rates.py

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+from decimal import Decimal
+from unittest.mock import patch, MagicMock
+
+from django.test import TestCase
+from django.utils import timezone
+
+from apps.currencies.models import Currency, ExchangeRateService
+from apps.currencies.exchange_rates.fetcher import ExchangeRateFetcher
+
+
+class ExchangeRateServiceFailureTrackingTests(TestCase):
+    """Tests for the failure count tracking functionality."""
+
+    def setUp(self):
+        """Set up test data."""
+        self.usd = Currency.objects.create(
+            code="USD", name="US Dollar", decimal_places=2, prefix="$ "
+        )
+        self.eur = Currency.objects.create(
+            code="EUR", name="Euro", decimal_places=2, prefix="€ "
+        )
+        self.eur.exchange_currency = self.usd
+        self.eur.save()
+
+        self.service = ExchangeRateService.objects.create(
+            name="Test Service",
+            service_type=ExchangeRateService.ServiceType.FRANKFURTER,
+            is_active=True,
+        )
+        self.service.target_currencies.add(self.eur)
+
+    def test_failure_count_increments_on_provider_error(self):
+        """Test that failure_count increments when provider raises an exception."""
+        self.assertEqual(self.service.failure_count, 0)
+
+        with patch.object(
+            self.service, "get_provider", side_effect=Exception("API Error")
+        ):
+            ExchangeRateFetcher._fetch_service_rates(self.service)
+
+        self.service.refresh_from_db()
+        self.assertEqual(self.service.failure_count, 1)
+
+    def test_failure_count_resets_on_success(self):
+        """Test that failure_count resets to 0 on successful fetch."""
+        # Set initial failure count
+        self.service.failure_count = 5
+        self.service.save()
+
+        # Mock a successful provider
+        mock_provider = MagicMock()
+        mock_provider.requires_api_key.return_value = False
+        mock_provider.get_rates.return_value = [(self.usd, self.eur, Decimal("0.85"))]
+        mock_provider.rates_inverted = False
+
+        with patch.object(self.service, "get_provider", return_value=mock_provider):
+            ExchangeRateFetcher._fetch_service_rates(self.service)
+
+        self.service.refresh_from_db()
+        self.assertEqual(self.service.failure_count, 0)
+
+    def test_failure_count_accumulates_across_fetches(self):
+        """Test that failure_count accumulates with consecutive failures."""
+        self.assertEqual(self.service.failure_count, 0)
+
+        with patch.object(
+            self.service, "get_provider", side_effect=Exception("API Error")
+        ):
+            ExchangeRateFetcher._fetch_service_rates(self.service)
+            self.service.refresh_from_db()
+            self.assertEqual(self.service.failure_count, 1)
+
+            ExchangeRateFetcher._fetch_service_rates(self.service)
+            self.service.refresh_from_db()
+            self.assertEqual(self.service.failure_count, 2)
+
+            ExchangeRateFetcher._fetch_service_rates(self.service)
+            self.service.refresh_from_db()
+            self.assertEqual(self.service.failure_count, 3)
+
+    def test_last_fetch_not_updated_on_failure(self):
+        """Test that last_fetch is NOT updated when a failure occurs."""
+        original_last_fetch = self.service.last_fetch
+        self.assertIsNone(original_last_fetch)
+
+        with patch.object(
+            self.service, "get_provider", side_effect=Exception("API Error")
+        ):
+            ExchangeRateFetcher._fetch_service_rates(self.service)
+
+        self.service.refresh_from_db()
+        self.assertIsNone(self.service.last_fetch)
+        self.assertEqual(self.service.failure_count, 1)
+
+    def test_last_fetch_updated_on_success(self):
+        """Test that last_fetch IS updated when fetch succeeds."""
+        self.assertIsNone(self.service.last_fetch)
+
+        mock_provider = MagicMock()
+        mock_provider.requires_api_key.return_value = False
+        mock_provider.get_rates.return_value = [(self.usd, self.eur, Decimal("0.85"))]
+        mock_provider.rates_inverted = False
+
+        with patch.object(self.service, "get_provider", return_value=mock_provider):
+            ExchangeRateFetcher._fetch_service_rates(self.service)
+
+        self.service.refresh_from_db()
+        self.assertIsNotNone(self.service.last_fetch)
+        self.assertEqual(self.service.failure_count, 0)