Hypothesis

-------------------

This release makes Hypothesis coverage aware. Hypothesis now runs all test
bodies under coverage, and uses this information to guide its testing.

The ``use_coverage`` setting can be used to disable
this behaviour if you want to test code that is sensitive to coverage being
enabled (either because of performance or interaction with the trace function).

The main benefits of this feature are:

* Hypothesis now observes when examples it discovers cover particular lines
or branches and stores them in the database for later.
* Hypothesis will make some use of this information to guide its exploration of
the search space and improve the examples it finds (this is currently used
only very lightly and will likely improve significantly in future releases).

This also has the following side-effects:

* Hypothesis now has an install time dependency on the :pypi:`coverage` package.
* Tests that are already running Hypothesis under coverage will likely get
faster.
* Tests that are not running under coverage now run their test bodies under
coverage by default.


This feature is only partially supported under pypy. It is significantly slower
than on CPython and is turned off by default as a result, but it should still
work correctly if you want to use it.

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This release is an internal change that affects how Hypothesis handles
calculating certain properties of strategies.

The primary effect of this is that it fixes a bug where use of
:func:`~hypothesis.strategies.deferred` could sometimes trigger an internal assertion
error. However the fix for this bug involved some moderately deep changes to
how Hypothesis handles certain constructs so you may notice some additional
knock-on effects.

In particular the way Hypothesis handles drawing data from strategies that
cannot generate any values has changed to bail out sooner than it previously
did. This may speed up certain tests, but it is unlikely to make much of a
difference in practice for tests that were not already failing with
Unsatisfiable.

-------------------

This is a patch release that fixes a bug in the :mod:`hypothesis.extra.pandas`
documentation where it incorrectly referred to :func:`~hypothesis.extra.pandas.column`
instead of :func:`~hypothesis.extra.pandas.columns`.

-------------------

This is a refactoring release. It moves a number of internal uses
of :func:`~python:collections.namedtuple` over to using attrs based classes, and removes a couple
of internal namedtuple classes that were no longer in use.

It should have no user visible impact.

-------------------

This release adds support for testing :pypi:`pandas` via the :ref:`hypothesis.extra.pandas <hypothesis-pandas>`
module.

It also adds a dependency on :pypi:`attrs`.

This work was funded by `Stripe <https://stripe.com/>`_.

-------------------

This release fixes some formatting and broken cross-references in the
documentation, which includes editing docstrings - and thus a patch release.