Testing Simple View

tests.py

class ExchangeAPITestCase(APITestCase):
    def setUp(self) -> None:
        self.valid_base_query_param = 'USD'
        self.valid_target_query_param = 'EUR'
        self.valid_amount_query_param = 12.12
        self.valid_convert_return_value = 1404.75
        self.valid_serializer_data = {
            'base': self.valid_base_query_param,
            'target': self.valid_target_query_param,
            'amount': self.valid_amount_query_param
        }

    @mock.patch.object(CurrencyConvertSerializer, 'is_valid')
    @mock.patch('currency_exchanger.serializers.CurrencyConvertSerializer.data',
                new_callable=PropertyMock)
    @mock.patch.object(ExchangeRateService, 'convert')
    def test_currency_convert_success(self, mock_is_valid, mock_data, mock_convert):
        mock_is_valid.return_value = None
        mock_data.return_value = self.valid_serializer_data
        mock_convert.return_value = self.valid_convert_return_value

        response = self.client.get(f"/api/exchange/?"
                                   f"base={self.valid_base_query_param}&"
                                   f"target={self.valid_target_query_param}&"
                                   f"amount={self.valid_amount_query_param}")

        self.assertTrue(mock_is_valid.called)
        self.assertTrue(mock_convert.called)
        self.assertTrue(mock_data.called)
#         print(mock_convert.call_count)
#         print(mock_is_valid.call_count)
#         print(mock_data.call_count)
        self.assertEqual(response.status_code, 200)
        self.assertDictEqual(response.data, {'result': self.valid_convert_return_value})
    # AssertionError: {'result': None} != {'result': 1404.75}
    # - {'result': None}
    # + {'result': 1404.75}

views.py

from rest_framework import status
from rest_framework.response import Response
from rest_framework.views import APIView

from .serializers import CurrencyConvertSerializer
from .services import ExchangeRateService


class CurrencyConvertAPIView(APIView):
    def get(self, *args, **kwargs):
        serializer = CurrencyConvertSerializer(data=self.request.query_params)
        serializer.is_valid(raise_exception=True)
        validated_data = serializer.data
        
        exchange_service = ExchangeRateService()
        result = exchange_service.convert(**validated_data)
        
        return Response({'result': result}, status=status.HTTP_200_OK)