How can I include special characters (tab, newline) in a python doctest result string?

Question

Given the following python script:

# dedupe.py
import re

def dedupe_whitespace(s,spacechars=\'\\t \'):
    \"\"\"Merge repeated whitespace characters.
    Examp         


        

Answer 1

This is basically YatharhROCK's answer, but a bit more explicit. You can use raw strings or double escaping. But why?

You need the string literal to contain valid Python code that, when interpreted, is the code you want to run/test. These both work:

#!/usr/bin/env python

def split_raw(val, sep='\n'):
  r"""Split a string on newlines (by default).

  >>> split_raw('alpha\nbeta\ngamma')
  ['alpha', 'beta', 'gamma']
  """
  return val.split(sep)


def split_esc(val, sep='\n'):
  """Split a string on newlines (by default).

  >>> split_esc('alpha\\nbeta\\ngamma')
  ['alpha', 'beta', 'gamma']
  """
  return val.split(sep)

import doctest
doctest.testmod()

The effect of using raw strings and the effect of double-escaping (escape the slash) both leaves in the string two characters, the slash and the n. This code is passed to the Python interpreter, which takes "slash then n" to mean "newline character" inside a string literal.

Use whichever you prefer.