105 lines
2.9 KiB
Plaintext
105 lines
2.9 KiB
Plaintext
Getting Started
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===================================
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.. _`easy_install`:
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**Compatibility**: Python 2.4-3.2, Jython, PyPy on Unix/Posix and Windows
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Installation
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----------------------------------------
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Installation options::
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easy_install -U pytest # or
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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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$ py.test --version
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If you get an error, checkout :ref:`installation issues`.
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Writing a simple test function with an assertion
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----------------------------------------------------------
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Let's create a small file with a test function testing a function
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computes a certain value::
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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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Now you can execute the test function::
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$ py.test test_sample.py
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========================= test session starts ==========================
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platform linux2 -- Python 2.6.5 -- pytest-2.0.0.dev4
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test path 1: test_sample.py
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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:4: AssertionError
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======================= 1 failed in 0.02 seconds =======================
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We got a failure because our little ``func(3)`` call did not return ``5``.
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A few notes on this little test invocation:
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* ``test_answer`` was identified as a test function because of the
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``test_`` prefix,
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* we conveniently used the standard `assert statement`_ and the failure
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report shows us the intermediate values.
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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 a test raises a certain 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 py
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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 py.test.raises(SystemExit):
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f()
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Running it with::
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$ py.test test_sysexit.py
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========================= test session starts ==========================
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platform linux2 -- Python 2.6.5 -- pytest-2.0.0.dev4
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test path 1: test_sysexit.py
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test_sysexit.py .
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======================= 1 passed in 0.01 seconds =======================
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.. For further ways to assert exceptions see the :pyfunc:`raises`
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where to go from here
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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` for virtualenv, test layout, genscript support
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* :ref:`apiref` for documentation and examples on writing Python tests
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* :ref:`examples` for more complex examples
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.. include:: links.inc
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