Detecting sequence in array

array_sequence.py

# How to detect sequence in an array

def is_sequence(arr):
    "Return True if the array is sequence."
    return (len(set(arr)) == len(arr)) and ((max(arr) - min(arr)) == (len(arr) - 1))

def test():
  "Test cases for the functions in poker program."
  "Test cases for the Array.sequence method."
  assert is_sequence([1,2,3,4,5]) == True
  assert is_sequence([5,1,2,3,4]) == True
  assert is_sequence([1,2,3,3,5]) == False
  return 'tests pass'

print test()