pytest autocompletion in Bash

Question

I am hoping to get Bash autocompletion to work with pytest. That is, suppose that I have a pytest file test_foo.py whose content is

def test_case_simple():
  pass

then entering pytest test_foo.py:: and pressing tab would give me test_case_simple. I know that Get pytest autocompletion in zshell is a related question but I am unable to get the same script working for bash (it gives me an error saying that compadd is unknown).

---

Followup: The script that I used is

#compdef pytest

_pytest_complete() {
    local curcontext="$curcontext" state line
    typeset -A opt_args
    compadd "$@" $( pytest --collect-only -q | head -n -2)
}

_pytest_complete "$@"

and the error I got is

compadd: command not found