running tests very fast

models.py

COLOR_CHOICES = (
    ('red', 'Red'),
    ('green', 'Green'),
    ('blue', 'Blue'),
)

class Vehicle(models.Model):
     year = models.CharField(max_length=4)
     color = models.CharField(max_length=30, choices = COLOR_CHOICES)

tasks.py

from models import Vehicle

class ReportManager(object):

    def __init__(self, title):
        self.error_list = []
        self.title = title
    
    def get_queryset(self):
        return Vehicle.objects.filter(color='blue')

    def change_vehicle_color_to_red(self, queryset):
        queryset.update(color='red')

    def run(self):
        queryset = self.get_queryset()
        self.change_vehicle_color_to_red(queryset)

        

test_tasks.py

from unittest import TestCase
from mock import patch, Mock

from tasks import ReportManager

class ReportManagerTest(TestCase):

    def setUp(self):
        self.manager = ReportManager(title='Foo')

    def test_instance(self):
        self.assertEqual(self.manager.error_list, [])
        self.assertEqual(self.manager.title, 'Foo')

    @patch('tasks.Vehicle')
    def test_get_queryset(self, _model):
        self.manager.get_queryset()
        _model.objects.filter.assert_called_once_with(color='blue')

    def test_change_vehicle_color_to_red(self):
        mock = Mock()
        self.manager.change_vehicle_color_to_red(mock)
        mock.update.assert_called_once_with(color='red')

    @patch('tasks.ReportManager.get_queryset')
    @patch('tasks.ReportManager.change_vehicle_color_to_red')
    def test_run(self, _change_vehicle_color_to_red, _get_queryset):
        _get_queryset.return_value = 'foo'
        self.manager.run()
        _get_queryset.assert_called_once_with()
        __change_vehicle_color_to_red.assert_called_once_with('foo')