236 lines
7.9 KiB
Plaintext
236 lines
7.9 KiB
Plaintext
Installation and Getting Started
|
|
===================================
|
|
|
|
**Compatibility**: Python 2.4-3.2, Jython, PyPy on Unix/Posix and Windows
|
|
|
|
.. _`getstarted`:
|
|
|
|
Installation
|
|
----------------------------------------
|
|
|
|
Installation options::
|
|
|
|
easy_install -U pytest # or
|
|
pip install -U pytest
|
|
|
|
To check your installation has installed the correct version::
|
|
|
|
$ py.test --version
|
|
This is py.test version 2.0.3, imported from /home/hpk/p/pytest/pytest.pyc
|
|
setuptools registered plugins:
|
|
pytest-xdist-1.6.dev3 at /home/hpk/p/pytest-xdist/xdist/plugin.pyc
|
|
pytest-incremental-0.1.0 at /home/hpk/venv/0/lib/python2.6/site-packages/pytest_incremental.pyc
|
|
|
|
If you get an error checkout :ref:`installation issues`.
|
|
|
|
.. _`simpletest`:
|
|
|
|
Our first test run
|
|
----------------------------------------------------------
|
|
|
|
Let's create a first test file with a simple test function::
|
|
|
|
# content of test_sample.py
|
|
def func(x):
|
|
return x + 1
|
|
|
|
def test_answer():
|
|
assert func(3) == 5
|
|
|
|
That's it. You can execute the test function now::
|
|
|
|
$ py.test
|
|
=========================== test session starts ============================
|
|
platform linux2 -- Python 2.6.6 -- pytest-2.0.3
|
|
collecting ... collected 1 items
|
|
|
|
test_sample.py F
|
|
|
|
================================= FAILURES =================================
|
|
_______________________________ test_answer ________________________________
|
|
|
|
def test_answer():
|
|
> assert func(3) == 5
|
|
E assert 4 == 5
|
|
E + where 4 = func(3)
|
|
|
|
test_sample.py:5: AssertionError
|
|
========================= 1 failed in 0.02 seconds =========================
|
|
|
|
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``.
|
|
|
|
.. note::
|
|
|
|
You can simply use the ``assert`` statement for asserting
|
|
expectations because intermediate values will be presented to you.
|
|
This is arguably easier than learning all the `the JUnit legacy
|
|
methods`_.
|
|
|
|
However, there remains one caveat to using simple asserts: your
|
|
assertion expression should better be side-effect free. Because
|
|
after an assertion failed py.test will re-evaluate the expression
|
|
in order to present intermediate values. You will get a nice warning
|
|
and you can easily fix it: compute the value ahead of the assert and
|
|
then do the assertion. Or maybe just use the assert "explicit message"
|
|
syntax::
|
|
|
|
assert expr, "message" # show "message" if expr is not True
|
|
|
|
.. _`the JUnit legacy methods`: http://docs.python.org/library/unittest.html#test-cases
|
|
|
|
.. _`assert statement`: http://docs.python.org/reference/simple_stmts.html#the-assert-statement
|
|
|
|
Asserting that a certain exception is raised
|
|
--------------------------------------------------------------
|
|
|
|
If you want to assert that some code raises an exception you can
|
|
use the ``raises`` helper::
|
|
|
|
# content of test_sysexit.py
|
|
import pytest
|
|
def f():
|
|
raise SystemExit(1)
|
|
|
|
def test_mytest():
|
|
with pytest.raises(SystemExit):
|
|
f()
|
|
|
|
Running it with, this time in "quiet" reporting mode::
|
|
|
|
$ py.test -q test_sysexit.py
|
|
collecting ... collected 1 items
|
|
.
|
|
1 passed in 0.01 seconds
|
|
|
|
.. todo:: For further ways to assert exceptions see the `raises`
|
|
|
|
Grouping multiple tests in a class
|
|
--------------------------------------------------------------
|
|
|
|
Once you start to have more than a few tests it often makes sense
|
|
to group tests logically, in classes and modules. Let's write a class
|
|
containing two tests::
|
|
|
|
# content of test_class.py
|
|
class TestClass:
|
|
def test_one(self):
|
|
x = "this"
|
|
assert 'h' in x
|
|
|
|
def test_two(self):
|
|
x = "hello"
|
|
assert hasattr(x, 'check')
|
|
|
|
The two tests are found because of the standard :ref:`test discovery`.
|
|
There is no need to subclass anything. We can simply
|
|
run the module by passing its filename::
|
|
|
|
$ py.test -q test_class.py
|
|
collecting ... collected 2 items
|
|
.F
|
|
================================= FAILURES =================================
|
|
____________________________ TestClass.test_two ____________________________
|
|
|
|
self = <test_class.TestClass instance at 0x142c320>
|
|
|
|
def test_two(self):
|
|
x = "hello"
|
|
> assert hasattr(x, 'check')
|
|
E assert False
|
|
E + where False = hasattr('hello', 'check')
|
|
|
|
test_class.py:8: AssertionError
|
|
1 failed, 1 passed in 0.03 seconds
|
|
|
|
The first test passed, the second failed. Again we can easily see
|
|
the intermediate values used in the assertion, helping us to
|
|
understand the reason for the failure.
|
|
|
|
Going functional: requesting a unique temporary directory
|
|
--------------------------------------------------------------
|
|
|
|
For functional tests one often needs to create some files
|
|
and pass them to application objects. py.test provides
|
|
the versatile :ref:`funcarg mechanism` which allows to request
|
|
arbitrary resources, for example a unique temporary directory::
|
|
|
|
# content of test_tmpdir.py
|
|
def test_needsfiles(tmpdir):
|
|
print tmpdir
|
|
assert 0
|
|
|
|
We list the name ``tmpdir`` in the test function signature and
|
|
py.test will lookup and call a factory to create the resource
|
|
before performing the test function call. Let's just run it::
|
|
|
|
$ py.test -q test_tmpdir.py
|
|
collecting ... collected 1 items
|
|
F
|
|
================================= FAILURES =================================
|
|
_____________________________ test_needsfiles ______________________________
|
|
|
|
tmpdir = local('/tmp/pytest-10/test_needsfiles0')
|
|
|
|
def test_needsfiles(tmpdir):
|
|
print tmpdir
|
|
> assert 0
|
|
E assert 0
|
|
|
|
test_tmpdir.py:3: AssertionError
|
|
----------------------------- Captured stdout ------------------------------
|
|
/tmp/pytest-10/test_needsfiles0
|
|
1 failed in 0.13 seconds
|
|
|
|
Before the test runs, a unique-per-test-invocation temporary directory
|
|
was created. More info at :ref:`tmpdir handling`.
|
|
|
|
You can find out what kind of builtin :ref:`funcargs` exist by typing::
|
|
|
|
py.test --funcargs # shows builtin and custom function arguments
|
|
|
|
where to go next
|
|
-------------------------------------
|
|
|
|
Here are a few suggestions where to go next:
|
|
|
|
* :ref:`cmdline` for command line invocation examples
|
|
* :ref:`good practises <goodpractises>` for virtualenv, test layout, genscript support
|
|
* :ref:`apiref` for documentation and examples on using py.test
|
|
* :ref:`plugins` managing and writing plugins
|
|
|
|
.. _`installation issues`:
|
|
|
|
Known Installation issues
|
|
------------------------------
|
|
|
|
easy_install or pip not found?
|
|
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
|
|
|
|
Consult `distribute docs`_ to install the ``easy_install``
|
|
tool on your machine. You may also use the older
|
|
`setuptools`_ project but it lacks bug fixes and does not
|
|
work on Python3. If you use Python2 you may also install pip_.
|
|
|
|
py.test not found on Windows despite installation?
|
|
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
|
|
|
|
.. _`Python for Windows`: http://www.imladris.com/Scripts/PythonForWindows.html
|
|
|
|
- **Windows**: If "easy_install" or "py.test" are not found
|
|
you need to add the Python script path to your ``PATH``, see here:
|
|
`Python for Windows`_. You may alternatively use an `ActivePython install`_
|
|
which does this for you automatically.
|
|
|
|
.. _`ActivePython install`: http://www.activestate.com/activepython/downloads
|
|
|
|
.. _`Jython does not create command line launchers`: http://bugs.jython.org/issue1491
|
|
|
|
- **Jython2.5.1 on Windows XP**: `Jython does not create command line launchers`_
|
|
so ``py.test`` will not work correctly. You may install py.test on
|
|
CPython and type ``py.test --genscript=mytest`` and then use
|
|
``jython mytest`` to run py.test for your tests to run with Jython.
|
|
|
|
:ref:`examples` for more complex examples
|
|
|
|
.. include:: links.inc
|