properly mock celery task that is being called inside another celery task

How to properly mock celery task that is being called inside another celery task? (dummy code below)

@app.task
def task1(smthg):
    do_so_basic_stuff_1
    do_so_basic_stuff_2
    other_thing(smthg)

@app.task
def task2(smthg):
    if condition:
        task1.delay(smthg[1])
    else:
        task1.delay(smthg)

I do have exact same structure of code in my_module. proj/cel/my_module.py I'm trying to write test in proj/tests/cel_test/test.py

Test function:

def test_this_thing(self):
    # firs I want to mock task1
    # i've tried to import it from my_module.py to test.py and then mock it from test.py namespace 
    # i've tried to import it from my_module.py and mock it
    # nothing worked for me

    # what I basically want to do 
    # mock task1 here
    # and then run task 2 (synchronous)
    task2.apply()
    # and then I want to check if task one was called 
    self.assertTrue(mocked_task1.called)