Djangoでテストデータを作成するときはsetUpTestDataを使う ref: http://qiita.com/tarunama/items/1dfb22650576f878f649

test_data.py

from test.common_data import UserFactory


class Test(TestCase):

    @classmethod
    def setUpTestData(cls):
        cls.user = UserFactory.create()

    def test_1(self):
        print(self.user.pk) # 1

    def test_2(self):
        print(self.user.pk) # 1