Tricks with nose and python

Nose is a very useful tool for running unittest in python. These are a few tricks you can use. Bellow is my test file - I called it test.py

# dummy case test 

class Test():

    def test_algo(self):
        assert 0 == 0, '0 is not equal to 0'

    def test_failed(self):
        print 'this will fail'
        assert 1 == 0, '0 is not equal to 1'

    def test_fail_inpdb(self):
        # div by 0
        1/0

Now let's see what is this about

1. first I use assert to check if the results match
2. based on assert the first function will pass and second will fail
3. the last function will trigger and Error not a Failure

# running with pdb so any Error not Failure will drop me into python debugger
$ nosetests  --pdb  test.py
.> /home/silviud/PROGS/PYTHON/wal/tests/test.py(14)test_fail_inpdb()
-> 1/0
(Pdb) l
  9             print 'this will fail'
 10             assert 1 == 0, '0 is not equal to 1'
 11     
 12         def test_fail_inpdb(self):
 13             # div by 0
 14  ->         1/0          #### this is the line that triggers the error
[EOF]
(Pdb) c
EF
======================================================================
ERROR: tests.test.Test.test_fail_inpdb
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/silviud/Environments/2.7/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/home/silviud/PROGS/PYTHON/wal/tests/test.py", line 14, in test_fail_inpdb
    1/0
ZeroDivisionError: integer division or modulo by zero

======================================================================
FAIL: tests.test.Test.test_failed
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/silviud/Environments/2.7/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/home/silviud/PROGS/PYTHON/wal/tests/test.py", line 10, in test_failed
    assert 1 == 0, '0 is not equal to 1'
AssertionError: 0 is not equal to 1
-------------------- >> begin captured stdout << ---------------------
this will fail

--------------------- >> end captured stdout << ----------------------

----------------------------------------------------------------------
Ran 3 tests in 8.453s

FAILED (errors=1, failures=1)

Now let's pretended that I run this regular and is part of my Continuous Integration server which so happen
to be running Jenkins. How can I integrate the python unittests with it ?!
Simple - nose has many plugins and one of them is xunit.

$ nosetests  --with-xunit test.py
....
$ cat nosetests.xml
<?xml version="1.0" encoding="UTF-8"?><testsuite name="nosetests" tests="3" errors="1" failures="1" skip="0"><testcase classname="tests.test.Test" name="test_algo" time="0.000" /><testcase classname="tests.test.Test" name="test_fail_inpdb" time="0.000"><error type="exceptions.ZeroDivisionError" message="integer division or modulo by zero"><![CDATA[Traceback (most recent call last):
  File "/usr/lib/python2.7/unittest/case.py", line 321, in run
    testMethod()
  File "/home/silviud/Environments/2.7/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/home/silviud/PROGS/PYTHON/wal/tests/test.py", line 14, in test_fail_inpdb
    1/0
ZeroDivisionError: integer division or modulo by zero
]]></error></testcase><testcase classname="tests.test.Test" name="test_failed" time="0.001"><failure type="exceptions.AssertionError" message="0 is not equal to 1&#10;-------------------- &gt;&gt; begin captured stdout &lt;&lt; ---------------------&#10;this will fail&#10;&#10;--------------------- &gt;&gt; end captured stdout &lt;&lt; ----------------------"><![CDATA[Traceback (most recent call last):
  File "/usr/lib/python2.7/unittest/case.py", line 321, in run
    testMethod()
  File "/home/silviud/Environments/2.7/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/home/silviud/PROGS/PYTHON/wal/tests/test.py", line 10, in test_failed
    assert 1 == 0, '0 is not equal to 1'
AssertionError: 0 is not equal to 1
-------------------- >> begin captured stdout << ---------------------
this will fail

--------------------- >> end captured stdout << ----------------------
]]></failure></testcase></testsuite>

Just by adding --with-xunit made nose to active the xunit plugin and it generated an xml file into nosetests.xml - this file can be used by Jenkins to take decisions if the build failed or not !