Assert Error: AssertionError

[AlexPetru]

Hi!

The function stergereTranzactie(list,zi) delete a number from a list.
The function testarestergereTranzactie() tests stergereTranzactie(list,zi).

How can I solve this error/How can I use "assert" in this situation?

def stergereTranzactie(list,zi):
    del(list[zi])

def testarestergereTranzactie():
    assert (stergereTranzactie([12, 13, 14, 15], 0)==[13, 14, 15])

def mainFunction():
    testarestergereTranzactie()
    
mainFunction()

Error:
Traceback (most recent call last):
  File "C:/Users/Petru/Desktop/test.py", line 12, in <module>
    mainFunction()
  File "C:/Users/Petru/Desktop/test.py", line 9, in mainFunction
    testarestergereTranzactie()
  File "C:/Users/Petru/Desktop/test.py", line 5, in testarestergereTranzactie
    assert (stergereTranzactie([12, 13, 14, 15], 0)==[13, 14, 15])
AssertionError

Thanks!