Different solutions for sum of powers of 2

sum_of_powers_of_2.py

#!/usr/bin/env python3

# example 1: brute force solution
def sum_of_powers_of_2_brute_force(power):
  # time complexity: O(n)
  return sum([pow(2, i) for i in range(power+1)])

def sum_of_powers_of_2(power):
  # time complexity: O(1)
  return pow(2, power+1) - 1

# test cases
def getTestCaseResult(actual, expected):
  return 'PASSED' if actual == expected else 'FAILED'

test_cases = [(2, 7), (4, 31), (6, 127), (8, 511)]
for fn in [sum_of_powers_of_2_brute_force, sum_of_powers_of_2]:
    for power, expected_result in test_cases:
      print(f'TestCase ({power}, {expected_result}) => ', getTestCaseResult(fn(power), expected_result))