test_awkward.py

import mock

class MyDatabaseAccessModule():
  def fetch_data_from_db(self):
    print('this one will also not be printed')
    return "the data"

class MyHTTPAPIModule():
  def fetch_data(self):
    print('this will never be printed')
    myDatabaseAccessObjInstance = MyDatabaseAccessModule()
    return myDatabaseAccessObjInstance.fetch_data_from_db()

@mock.patch("test_awkward.MyHTTPAPIModule.fetch_data", mock.MagicMock(return_value="the data"))
def test_fetch_data():
  instanceOfTheRealMyHTTPAPIModuleObject = MyHTTPAPIModule()
  # the real function is not called here
  result = instanceOfTheRealMyHTTPAPIModuleObject.fetch_data()
  assert result == "the data"
  
# save this file and run
# pytest -vv -s test_awkward.py

test_sum.py

class MyMathClass():
  def sum_of_two_numbers(self, a, b):
    return a+b


def test_sum_of_two_numbers():
  myMathObjInstance = MyMathClass()
  result = myMathObjInstance.sum_of_two_numbers(1,1)
  assert result == 2
  
# save this file and run
# pytest -vv -s test_sum.py