Exception statement not covered by self.assertRaises in python unit test cases

Question

This is my function:

def get_value(request, param):
  s = get_string(request, param)
  value = re.search('(\\d\\d\\d\\d)-(\\d\\d)-(\\d\\d)', s)
  if not value:
    print 'match not found!'  
    raise Exception('incorrect format: %s' % param)

test function:

def test_get_value(self):
    m = test_mocks.HttpRequestMock(REQUEST = {'start_date': '2011.07.31'})
    print '*************************'
    print 'date format changed'
    self.assertRaises(Exception, get_value, (m, 'start_date'))
    print '*********************

get_value doesn't print: match not found!

Answer 1

It seems there is some issue with your python version. I guess you are using python below version 2.6. Try passing function parameters as other arguments to function i.e. do not put them inside tuple. Try this.

self.assertRaises(Exception, helpers.get_value, m, 'start_date')

Answer 2

You're passing the arguments to assertRaises() incorrectly, you should pass them like this:

self.assertRaises(Exception, helpers.get_value, m, 'start_date')

Here's a full test case that works for me. The first test passes, and the second one fails.

import re
from unittest import TestCase

def get_value(s):
    value = re.search('(\\d\\d\\d\\d)-(\\d\\d)-(\\d\\d)', s)
    if not value:
        raise ValueError('incorrect format: %s' % s)

class TesterScratch(TestCase):
    # this one passes
    def test_get_value(self):
        s = '2011.07.31'
        self.assertRaises(ValueError, get_value, s)

    # this one fails, because the format is actually correct
    def test_get_value2(self):
        s = '2011-07-31'
        self.assertRaises(ValueError, get_value, s)