.. _`unittest.TestCase`:

Support for unittest.TestCase
=====================================================================

py.test has limited support for running Python `unittest.py style`_ tests.
It will automatically collect ``unittest.TestCase`` subclasses
and their ``test`` methods in test files.  It will invoke
``setUp/tearDown`` methods but also perform py.test's standard ways
of treating tests such as IO capturing::

    # content of test_unittest.py

    import unittest
    class MyTest(unittest.TestCase):
        def setUp(self):
            print ("hello") # output is captured
        def test_method(self):
            x = 1
            self.assertEquals(x, 3)
       
Running it yields::

    $ py.test test_unittest.py
    =========================== test session starts ============================
    platform linux2 -- Python 2.7.3 -- pytest-2.3.0.dev12
    plugins: xdist, bugzilla, cache, oejskit, cli, timeout, pep8, cov
    collecting ... collected 1 items
    
    test_unittest.py F
    
    ================================= FAILURES =================================
    ____________________________ MyTest.test_method ____________________________
    
    self = <test_unittest.MyTest testMethod=test_method>
    
        def test_method(self):
            x = 1
    >       self.assertEquals(x, 3)
    E       AssertionError: 1 != 3
    
    test_unittest.py:8: AssertionError
    ----------------------------- Captured stdout ------------------------------
    hello
    ========================= 1 failed in 0.03 seconds =========================

.. _`unittest.py style`: http://docs.python.org/library/unittest.html

Moreover, you can use the new :ref:`@pytest.setup functions <@pytest.setup>` 
functions and make use of pytest's unique :ref:`funcarg mechanism` in your
test suite::

    # content of test_unittest_funcargs.py
    import pytest
    import unittest

    class MyTest(unittest.TestCase):
        @pytest.setup()
        def chdir(self, tmpdir):
            tmpdir.chdir() # change to pytest-provided temporary directory
            tmpdir.join("samplefile.ini").write("# testdata")

        def test_method(self):
            s = open("samplefile.ini").read() 
            assert "testdata" in s

Running this file should give us one passed test because the setup
function took care to prepare a directory with some test data
which the unittest-testcase method can now use::

    $ py.test -q test_unittest_funcargs.py
    collecting ... collected 1 items
    .
    1 passed in 0.28 seconds

If you want to make a database attribute available on unittest.TestCases
instances, based on a marker, you can do it using :ref:`pytest.mark`` and
:ref:`setup functions`::

    # content of test_unittest_marked_db.py
    import pytest
    import unittest

    @pytest.factory()
    def db():
        class DummyDB:
            x = 1
        return DummyDB()

    @pytest.setup()
    def stick_db_to_self(request, db):
        if hasattr(request.node.markers, "needsdb"):
            request.instance.db = db

    class MyTest(unittest.TestCase):
        def test_method(self):
            assert not hasattr(self, "db")

        @pytest.mark.needsdb
        def test_method2(self):
            assert self.db.x == 1

Running it passes both tests, one of which will see a ``db`` attribute
because of the according ``needsdb`` marker::

    $ py.test -q test_unittest_marked_db.py
    collecting ... collected 2 items
    ..
    2 passed in 0.03 seconds