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Diffstat (limited to 'docs/fuzzy.rst')
| -rw-r--r-- | docs/fuzzy.rst | 39 |
1 files changed, 37 insertions, 2 deletions
diff --git a/docs/fuzzy.rst b/docs/fuzzy.rst index 1480419..6b06608 100644 --- a/docs/fuzzy.rst +++ b/docs/fuzzy.rst @@ -8,6 +8,8 @@ Some tests may be interested in testing with fuzzy, random values. This is handled by the :mod:`factory.fuzzy` module, which provides a few random declarations. +.. note:: Use ``import factory.fuzzy`` to load this module. + FuzzyAttribute -------------- @@ -62,8 +64,11 @@ FuzzyChoice The :class:`FuzzyChoice` fuzzer yields random choices from the given iterable. - .. note:: The passed in :attr:`choices` will be converted into a list at - declaration time. + .. note:: The passed in :attr:`choices` will be converted into a list upon + first use, not at declaration time. + + This allows passing in, for instance, a Django queryset that will + only hit the database during the database, not at import time. .. attribute:: choices @@ -338,3 +343,33 @@ They should inherit from the :class:`BaseFuzzyAttribute` class, and override its The method responsible for generating random values. *Must* be overridden in subclasses. + + +Managing randomness +------------------- + +Using :mod:`random` in factories allows to "fuzz" a program efficiently. +However, it's sometimes required to *reproduce* a failing test. + +:mod:`factory.fuzzy` uses a separate instance of :class:`random.Random`, +and provides a few helpers for this: + +.. method:: get_random_state() + + Call :meth:`get_random_state` to retrieve the random generator's current + state. + +.. method:: set_random_state(state) + + Use :meth:`set_random_state` to set a custom state into the random generator + (fetched from :meth:`get_random_state` in a previous run, for instance) + +.. method:: reseed_random(seed) + + The :meth:`reseed_random` function allows to load a chosen seed into the random generator. + + +Custom :class:`BaseFuzzyAttribute` subclasses **SHOULD** +use :obj:`factory.fuzzy._random` as a randomness source; this ensures that +data they generate can be regenerated using the simple state from +:meth:`get_random_state`. |