Python:What's wrong in my unit testing code?

Question

I have two files "testable.py":

def joiner(x,y):
 return x+y 

"test_testable.py":

import unittest
import testable
class TestTestable(unittest.TestCase):
 def setUp(self):
 self.seq = ['a','b','1']
 self.seq2 = ['b','c',1]
 def test_joiner(self):
 for each in self.seq:
 for eachy in self.seq2:
 self.assertRaises(TypeError,testable.joiner(each,eachy))
if __name__ == '__main__':
 unittest.main()

Now when I run the test I get:

ERROR: test_joiner (test_testable.TestTestable)
----------------------------------------------------------------------
Traceback (most recent call last):
 File "/home/rajat/collective_knowledge/test_testable.py", line 16, in test_joiner
 self.assertRaises(TypeError,testable.joiner(each,eachy),(each,eachy))
 File "/home/rajat/collective_knowledge/testable.py", line 11, in joiner
 return x+y
TypeError: cannot concatenate 'str' and 'int' objects
----------------------------------------------------------------------
Ran 1 test in 0.000s
FAILED (errors=1)

What am I doing wrong?

Answer 1

You're miss using assertRaises it should be:

self.assertRaises(TypeError,testable.joiner, (each,eachy))

Or just use it as a context manager if you're using python2.7 and above or unittest2:

with self.assertRaises(TypeError):
 testable.joiner(each,eachy)

EDIT :

You should also replace self.seq2 = [1,2,3] for example.

• Rajat Saxena: FAIL: test_joiner (test_testable.TestTestable) ---------------------------------------------------------------------- Traceback (most recent call last): File "/home/rajat/collective_knowledge/test_testable.py", line 17, in test_joiner testable.joiner(each,eachy) AssertionError: TypeError not raised ---------------------------------------------------------------------- Ran 1 test in 0.001s FAILED (failures=1)
• mouad: That's because your testing data is wrong (at least from the test) b/c concatenating two strings is correct, the only one that will make your test succeed are the one with '*' + 1, so i think you want to do: self.seq2 = [1,2,3]
• Rajat Saxena: oh thanks,Also can you suggest me a nice guide to unit testing(esp. for django)?
• mouad: IMHO the doc (docs.djangoproject.com/en/dev/topics/testing) is a good reference.
• Kamal: @Rajat You should write separate tests for valid inputs (positive tests) and invalid inputs (negative).

Answer 2

In

for each in self.seq:
 for eachy in self.seq2

each could be 'a' and eachy could be 1

You can't add 'a' and 1 so the test fails.

• Rajat Saxena: Yeah,That's what I am testing.It should raise TypeError and my test code should tell that it's raised