diff --git a/doc/en/yieldfixture.txt b/doc/en/yieldfixture.txt index f3cc542dc..0fc7b5099 100644 --- a/doc/en/yieldfixture.txt +++ b/doc/en/yieldfixture.txt @@ -9,17 +9,9 @@ Fixture functions using "yield" / context manager integration pytest-2.4 allows fixture functions to seamlessly use a ``yield`` instead of a ``return`` statement to provide a fixture value while otherwise -fully supporting all other fixture features. +fully supporting all other fixture features. -.. note:: - - "yielding" fixture values is an experimental feature and its exact - declaration may change later but earliest in a 2.5 release. You can thus - safely use this feature in the 2.4 series but may need to adapt later. - Test functions themselves will not need to change (as a general - feature, they are ignorant of how fixtures are setup). - -Let's look at a simple standalone-example using the new ``yield`` syntax:: +Let's look at a simple standalone-example using the ``yield`` syntax:: # content of test_yield.py @@ -72,24 +64,25 @@ The file ``f`` will be closed after the test finished execution because the Python ``file`` object supports finalization when the ``with`` statement ends. -Note that the new syntax is fully integrated with using ``scope``, -``params`` and other fixture features. Changing existing -fixture functions to use ``yield`` is thus straight forward. +Note that the yield fixture form supports all other fixture +features such as ``scope``, ``params``, etc., thus changing existing +fixture functions to use ``yield`` is straightforward. + +.. note:: + + While the ``yield`` syntax is similar to what + :py:func:`contextlib.contextmanager` decorated functions + provide, with pytest fixture functions the part after the + "yield" will always be invoked, independently from the + exception status of the test function which uses the fixture. + This behaviour makes sense if you consider that many different + test functions might use a module or session scoped fixture. + Discussion and future considerations / feedback ++++++++++++++++++++++++++++++++++++++++++++++++++++ -The yield-syntax has been discussed by pytest users extensively. -In general, the advantages of the using a ``yield`` fixture syntax are: - -- easy provision of fixtures in conjunction with context managers. - -- no need to register a callback, providing for more synchronous - control flow in the fixture function. Also there is no need to accept - the ``request`` object into the fixture function just for providing - finalization code. - -However, there are also limitations or foreseeable irritations: +There are some topics that are worth mentioning: - usually ``yield`` is used for producing multiple values. But fixture functions can only yield exactly one value. @@ -100,24 +93,8 @@ However, there are also limitations or foreseeable irritations: :ref:`fixture parametrization ` mechanisms together with ``yield``-style fixtures. -- the ``yield`` syntax is similar to what - :py:func:`contextlib.contextmanager` decorated functions - provide. With pytest fixture functions, the "after yield" part will - always be invoked, independently from the exception status - of the test function which uses the fixture. The pytest - behaviour makes sense if you consider that many different - test functions might use a module or session scoped fixture. - Some test functions might raise exceptions and others not, - so how could pytest re-raise a single exception at the - ``yield`` point in the fixture function? - - lastly ``yield`` introduces more than one way to write fixture functions, so what's the obvious way to a newcomer? - Newcomers reading the docs will see feature examples using the - ``return`` style so should use that, if in doubt. - Others can start experimenting with writing yield-style fixtures - and possibly help evolving them further. -If you want to feedback or participate in the ongoing -discussion, please join our :ref:`contact channels`. -you are most welcome. +If you want to feedback or participate in discussion of the above +topics, please join our :ref:`contact channels`, you are most welcome.