199 lines
6.5 KiB
ReStructuredText
199 lines
6.5 KiB
ReStructuredText
Installation and Getting Started
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===================================
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**Pythons**: Python 2.7, 3.4, 3.5, 3.6, Jython, PyPy-2.3
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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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**dependencies**: `py <http://pypi.python.org/pypi/py>`_,
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`colorama (Windows) <http://pypi.python.org/pypi/colorama>`_,
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**documentation as PDF**: `download latest <https://media.readthedocs.org/pdf/pytest/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::
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pip install -U pytest
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To check your installation has installed the correct version::
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$ pytest --version
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This is pytest version 3.x.y, imported from $PYTHON_PREFIX/lib/python3.5/site-packages/pytest.py
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.. _`simpletest`:
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Our first test run
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----------------------------------------------------------
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Let's create a first test file with a simple test function::
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# content of test_sample.py
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def func(x):
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return x + 1
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def test_answer():
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assert func(3) == 5
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That's it. You can execute the test function now::
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$ pytest
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=========================== test session starts ============================
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platform linux -- Python 3.x.y, pytest-3.x.y, py-1.x.y, pluggy-0.x.y
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rootdir: $REGENDOC_TMPDIR, inifile:
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collected 1 item
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test_sample.py F [100%]
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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 0.12 seconds =========================
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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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Running multiple tests
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----------------------------------------------------------
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``pytest`` will run all files in the current directory and its subdirectories of the form test_*.py or \*_test.py. More generally, it follows :ref:`standard test discovery rules <test discovery>`.
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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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$ pytest -q test_sysexit.py
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. [100%]
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1 passed in 0.12 seconds
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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(object):
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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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$ pytest -q test_class.py
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.F [100%]
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================================= FAILURES =================================
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____________________________ TestClass.test_two ____________________________
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self = <test_class.TestClass object at 0xdeadbeef>
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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 AssertionError: assert False
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E + where False = hasattr('hello', 'check')
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test_class.py:8: AssertionError
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1 failed, 1 passed in 0.12 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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``pytest`` 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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$ pytest -q test_tmpdir.py
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F [100%]
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================================= FAILURES =================================
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_____________________________ test_needsfiles ______________________________
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tmpdir = local('PYTEST_TMPDIR/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 call ---------------------------
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PYTEST_TMPDIR/test_needsfiles0
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1 failed in 0.12 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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pytest --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 practices <goodpractices>` for virtualenv, test layout
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* :ref:`existingtestsuite` for working with pre-existing tests
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* :ref:`fixtures` for providing a functional baseline to your tests
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* :ref:`plugins` managing and writing plugins
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.. include:: links.inc
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