229 lines
7.4 KiB
Plaintext
229 lines
7.4 KiB
Plaintext
Installation and Getting Started
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===================================
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**Pythons**: Python 2.4-3.3, Jython, PyPy
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**Platforms**: Unix/Posix and Windows
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**PyPI package name**: `pytest <http://pypi.python.org/pypi/pytest>`_
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**documentation as PDF**: `download latest <http://pytest.org/latest/pytest.pdf>`_
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.. _`getstarted`:
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.. _installation:
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Installation
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----------------------------------------
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Installation options::
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pip install -U pytest # or
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easy_install -U pytest
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To check your installation has installed the correct version::
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$ py.test --version
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This is py.test version 2.4.2, imported from /home/hpk/p/pytest/.tox/regen/local/lib/python2.7/site-packages/pytest.pyc
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If you get an error checkout :ref:`installation issues`.
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.. _`simpletest`:
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Our first test run
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----------------------------------------------------------
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Let's create a first test file with a simple test function::
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# content of test_sample.py
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def func(x):
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return x + 1
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def test_answer():
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assert func(3) == 5
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That's it. You can execute the test function now::
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$ py.test
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=========================== test session starts ============================
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platform linux2 -- Python 2.7.3 -- pytest-2.4.2
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collected 1 items
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test_sample.py F
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================================= FAILURES =================================
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_______________________________ test_answer ________________________________
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def test_answer():
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> assert func(3) == 5
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E assert 4 == 5
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E + where 4 = func(3)
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test_sample.py:5: AssertionError
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========================= 1 failed in 0.01 seconds =========================
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py.test found the ``test_answer`` function by following :ref:`standard test discovery rules <test discovery>`, basically detecting the ``test_`` prefixes. We got a failure report because our little ``func(3)`` call did not return ``5``.
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.. note::
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You can simply use the ``assert`` statement for asserting test
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expectations. pytest's :ref:`assert introspection` will intelligently
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report intermediate values of the assert expression freeing
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you from the need to learn the many names of `JUnit legacy methods`_.
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.. _`JUnit legacy methods`: http://docs.python.org/library/unittest.html#test-cases
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.. _`assert statement`: http://docs.python.org/reference/simple_stmts.html#the-assert-statement
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Asserting that a certain exception is raised
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--------------------------------------------------------------
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If you want to assert that some code raises an exception you can
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use the ``raises`` helper::
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# content of test_sysexit.py
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import pytest
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def f():
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raise SystemExit(1)
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def test_mytest():
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with pytest.raises(SystemExit):
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f()
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Running it with, this time in "quiet" reporting mode::
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$ py.test -q test_sysexit.py
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.
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1 passed in 0.01 seconds
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.. todo:: For further ways to assert exceptions see the `raises`
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Grouping multiple tests in a class
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--------------------------------------------------------------
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Once you start to have more than a few tests it often makes sense
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to group tests logically, in classes and modules. Let's write a class
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containing two tests::
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# content of test_class.py
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class TestClass:
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def test_one(self):
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x = "this"
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assert 'h' in x
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def test_two(self):
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x = "hello"
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assert hasattr(x, 'check')
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The two tests are found because of the standard :ref:`test discovery`.
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There is no need to subclass anything. We can simply
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run the module by passing its filename::
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$ py.test -q test_class.py
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.F
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================================= FAILURES =================================
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____________________________ TestClass.test_two ____________________________
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self = <test_class.TestClass instance at 0x1e1f518>
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def test_two(self):
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x = "hello"
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> assert hasattr(x, 'check')
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E assert hasattr('hello', 'check')
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test_class.py:8: AssertionError
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1 failed, 1 passed in 0.01 seconds
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The first test passed, the second failed. Again we can easily see
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the intermediate values used in the assertion, helping us to
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understand the reason for the failure.
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Going functional: requesting a unique temporary directory
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--------------------------------------------------------------
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For functional tests one often needs to create some files
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and pass them to application objects. pytest provides
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:ref:`builtinfixtures` which allow to request arbitrary
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resources, for example a unique temporary directory::
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# content of test_tmpdir.py
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def test_needsfiles(tmpdir):
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print tmpdir
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assert 0
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We list the name ``tmpdir`` in the test function signature and
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py.test will lookup and call a fixture factory to create the resource
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before performing the test function call. Let's just run it::
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$ py.test -q test_tmpdir.py
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F
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================================= FAILURES =================================
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_____________________________ test_needsfiles ______________________________
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tmpdir = local('/tmp/pytest-186/test_needsfiles0')
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def test_needsfiles(tmpdir):
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print tmpdir
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> assert 0
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E assert 0
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test_tmpdir.py:3: AssertionError
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----------------------------- Captured stdout ------------------------------
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/tmp/pytest-186/test_needsfiles0
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1 failed in 0.01 seconds
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Before the test runs, a unique-per-test-invocation temporary directory
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was created. More info at :ref:`tmpdir handling`.
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You can find out what kind of builtin :ref:`fixtures` exist by typing::
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py.test --fixtures # shows builtin and custom fixtures
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Where to go next
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-------------------------------------
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Here are a few suggestions where to go next:
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* :ref:`cmdline` for command line invocation examples
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* :ref:`good practises <goodpractises>` for virtualenv, test layout, genscript support
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* :ref:`fixtures` for providing a functional baseline to your tests
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* :ref:`apiref` for documentation and examples on using py.test
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* :ref:`plugins` managing and writing plugins
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.. _`installation issues`:
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Known Installation issues
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------------------------------
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easy_install or pip not found?
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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.. _`install pip`: http://www.pip-installer.org/en/latest/index.html
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`Install pip`_ for a state of the art python package installer.
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Install `setuptools`_ to get ``easy_install`` which allows to install
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``.egg`` binary format packages in addition to source-based ones.
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py.test not found on Windows despite installation?
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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.. _`Python for Windows`: http://www.imladris.com/Scripts/PythonForWindows.html
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- **Windows**: If "easy_install" or "py.test" are not found
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you need to add the Python script path to your ``PATH``, see here:
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`Python for Windows`_. You may alternatively use an `ActivePython install`_
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which does this for you automatically.
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.. _`ActivePython install`: http://www.activestate.com/activepython/downloads
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.. _`Jython does not create command line launchers`: http://bugs.jython.org/issue1491
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- **Jython2.5.1 on Windows XP**: `Jython does not create command line launchers`_
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so ``py.test`` will not work correctly. You may install py.test on
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CPython and type ``py.test --genscript=mytest`` and then use
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``jython mytest`` to run py.test for your tests to run with Jython.
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:ref:`examples` for more complex examples
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.. include:: links.inc
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