Mocking in shell scripts

mocks.sh

#!/usr/bin/env bash

shopt -s expand_aliases

curl_mock() {
  local success
  [ "$1" == "success" ] && success=0 || success=1

  shift
  if [ $success -eq 0 ]; then
    echo "SUCCESS with args $*";
  else
    echo "FAILURE with args $*";
  fi
  return $success;
}

alias curl="curl_mock success $*"
curl BLA BLA BLA

alias curl="curl_mock failure $*"
curl TOO BAD