test: add starting tests

app/apps/currencies/tests.py

@@ -1,3 +1,92 @@
-from django.test import TestCase
+from decimal import Decimal
 
-# Create your tests here.
+from django.core.exceptions import ValidationError
+from django.db import IntegrityError
+from django.test import TestCase
+from django.utils import timezone
+
+from apps.currencies.models import Currency, ExchangeRate
+
+
+class CurrencyTests(TestCase):
+    def test_currency_creation(self):
+        """Test basic currency creation"""
+        currency = Currency.objects.create(
+            code="USD", name="US Dollar", decimal_places=2, prefix="$ ", suffix=" END "
+        )
+        self.assertEqual(str(currency), "US Dollar")
+        self.assertEqual(currency.code, "USD")
+        self.assertEqual(currency.decimal_places, 2)
+        self.assertEqual(currency.prefix, "$ ")
+        self.assertEqual(currency.suffix, " END ")
+
+    def test_currency_decimal_places_validation(self):
+        """Test decimal places validation for maximum value"""
+        currency = Currency(
+            code="TEST",
+            name="Test Currency",
+            decimal_places=31,  # Should fail as max is 30
+        )
+        with self.assertRaises(ValidationError):
+            currency.full_clean()
+
+    def test_currency_decimal_places_negative(self):
+        """Test decimal places validation for negative value"""
+        currency = Currency(
+            code="TEST",
+            name="Test Currency",
+            decimal_places=-1,  # Should fail as min is 0
+        )
+        with self.assertRaises(ValidationError):
+            currency.full_clean()
+
+    def test_currency_unique_code(self):
+        """Test that currency codes must be unique"""
+        Currency.objects.create(code="USD", name="US Dollar", decimal_places=2)
+        with self.assertRaises(IntegrityError):
+            Currency.objects.create(code="USD", name="Another Dollar", decimal_places=2)
+
+    def test_currency_unique_name(self):
+        """Test that currency names must be unique"""
+        Currency.objects.create(code="USD", name="US Dollar", decimal_places=2)
+        with self.assertRaises(IntegrityError):
+            Currency.objects.create(code="USD2", name="US Dollar", decimal_places=2)
+
+
+class ExchangeRateTests(TestCase):
+    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="€ "
+        )
+
+    def test_exchange_rate_creation(self):
+        """Test basic exchange rate creation"""
+        rate = ExchangeRate.objects.create(
+            from_currency=self.usd,
+            to_currency=self.eur,
+            rate=Decimal("0.85"),
+            date=timezone.now(),
+        )
+        self.assertEqual(rate.rate, Decimal("0.85"))
+        self.assertIn("USD to EUR", str(rate))
+
+    def test_unique_exchange_rate_constraint(self):
+        """Test that duplicate exchange rates for same currency pair and date are prevented"""
+        date = timezone.now()
+        ExchangeRate.objects.create(
+            from_currency=self.usd,
+            to_currency=self.eur,
+            rate=Decimal("0.85"),
+            date=date,
+        )
+        with self.assertRaises(Exception):  # Could be IntegrityError
+            ExchangeRate.objects.create(
+                from_currency=self.usd,
+                to_currency=self.eur,
+                rate=Decimal("0.86"),
+                date=date,
+            )