------------------Features^^^^^^^^- Switch pip invocations to use the module ``-m pip`` instead of direct invocation. This could helpavoid some of the shebang limitations.  - by :user:`gaborbernat` (`935 <https://github.com/tox-dev/tox/issues/935>`_)- Ability to specify package requirements for the tox run via the ``tox.ini`` (``tox`` section under key ``requires`` - PEP-508 style): can be used to specify both plugin requirements or build dependencies. - by :user:`gaborbernat` (`783 <https://github.com/tox-dev/tox/issues/783>`_)- Allow to run multiple tox instances in parallel by providing the``--parallel--safe-build`` flag. - by :user:`gaborbernat` (`849 <https://github.com/tox-dev/tox/issues/849>`_)

------------------Bugfixes^^^^^^^^- A caching issue that caused the ``develop-inst-nodeps`` action, whichreinstalls the package under test, to always run has been resolved. The``develop-inst-noop`` action, which, as the name suggests, is a no-op, will nowrun unless there are changes to ``setup.py`` or ``setup.cfg`` files that havenot been reflected - by stephenfin (`909 <https://github.com/tox-dev/tox/issues/909>`_)Features^^^^^^^^- Python version testenvs are now automatically detected instead of comparingagainst a hard-coded list of supported versions.  This enables ``py38`` andeventually ``py39`` / ``py40`` / etc. to work without requiring an upgrade to``tox``.  As such, the following public constants are now deprecated(and scheduled for removal in ``tox`` 4.0: ``CPYTHON_VERSION_TUPLES``,``PYPY_VERSION_TUPLES``, ``OTHER_PYTHON_INTERPRETERS``, and ``DEFAULT_FACTORS`` -by :user:`asottile` (`914 <https://github.com/tox-dev/tox/issues/914>`_)Documentation^^^^^^^^^^^^^- Add a system overview section on the index page that explains briefly how tox works -by :user:`gaborbernat`. (`867 <https://github.com/tox-dev/tox/issues/867>`_)

------------------Bugfixes^^^^^^^^- Revert "Fix bug with incorrectly defactorized dependencies (`772 <https://github.com/tox-dev/tox/issues/772>`_)" due to a regression (`(799) <https://github.com/tox-dev/tox/issues/899>`_) - by :user:`obestwalter`

------------------Bugfixes^^^^^^^^- PyPi documentation for ``3.1.0`` is broken. Added test to check for this, andfix it by :user:`gaborbernat`. (`879<https://github.com/tox-dev/tox/issues/879>`_)

------------------Bugfixes^^^^^^^^- Add ``ignore_basepython_conflict``, which determines whether conflicting``basepython`` settings for environments containing default factors, such as``py27`` or ``django18-py35``, should be ignored or result in warnings. Thiswas a common source of misconfiguration and is rarely, if ever, desirable froma user perspective - by :user:`stephenfin` (`477 <https://github.com/tox-dev/tox/issues/477>`_)- Fix bug with incorrectly defactorized dependencies (deps passed to pip were not de-factorized) - by :user:`bartsanchez` (`706 <https://github.com/tox-dev/tox/issues/706>`_)Features^^^^^^^^- Add support for multiple PyPy versions using default factors. This allows youto use, for example, ``pypy27`` knowing that the correct intepreter will beused by default - by :user:`stephenfin` (`19 <https://github.com/tox-dev/tox/issues/19>`_)- Add support to explicitly invoke interpreter directives for environments withlong path lengths. In the event that ``tox`` cannot invoke scripts with asystem-limited shebang (e.x. a Linux host running a Jenkins Pipeline), a usercan set the environment variable ``TOX_LIMITED_SHEBANG`` to workaround thesystem's limitation (e.x. ``export TOX_LIMITED_SHEBANG=1``) - by :user:`jdknight` (`794 <https://github.com/tox-dev/tox/issues/794>`_)- introduce a constants module to be used internally and as experimental API - by :user:`obestwalter` (`798 <https://github.com/tox-dev/tox/issues/798>`_)- Make ``py2`` and ``py3`` aliases also resolve via ``py`` on windows by :user:`asottile`. This enables the following things:``tox -e py2`` and ``tox -e py3`` work on windows (they already work on posix); and setting ``basepython=python2`` or ``basepython=python3`` now works on windows. (`856 <https://github.com/tox-dev/tox/issues/856>`_)- Replace the internal version parsing logic from the not well tested `PEP-386 <https://www.python.org/dev/peps/pep-0386/>`_ parser for the more general `PEP-440 <https://www.python.org/dev/peps/pep-0440/>`_. `packaging >= 17.1 <https://pypi.org/project/packaging/>`_ is now an install dependency by :user:`gaborbernat`. (`860 <https://github.com/tox-dev/tox/issues/860>`_)Documentation^^^^^^^^^^^^^- extend the plugin documentation and make lot of small fixes and improvements - by :user:`obestwalter` (`797 <https://github.com/tox-dev/tox/issues/797>`_)- tidy up tests - remove unused fixtures, update old cinstructs, etc. - by :user:`obestwalter` (`799 <https://github.com/tox-dev/tox/issues/799>`_)- Various improvements to documentation: open browser once documentation generation is done, show Github/Travis info on documentation page, remove duplicate header for changelog, generate unreleased news as DRAFT on top of changelog, make the changelog page more compact and readable (width up to 1280px) by :user:`gaborbernat` (`859 <https://github.com/tox-dev/tox/issues/859>`_)Miscellaneous^^^^^^^^^^^^^- filter out unwanted files in package - by :user:`obestwalter` (`754 <https://github.com/tox-dev/tox/issues/754>`_)- make the already existing implicit API explicit - by :user:`obestwalter` (`800 <https://github.com/tox-dev/tox/issues/800>`_)- improve tox quickstart and corresponding tests - by :user:`obestwalter` (`801 <https://github.com/tox-dev/tox/issues/801>`_)- tweak codecov settings via .codecov.yml - by :user:`obestwalter` (`802 <https://github.com/tox-dev/tox/issues/802>`_)

------------------Bugfixes^^^^^^^^- Write directly to stdout buffer if possible to prevent str vs bytes issues -by asottile (`426 <https://github.com/tox-dev/tox/issues/426>`_)- fix 672 reporting to json file when skip-missing-interpreters option is used- by r2dan (`672 <https://github.com/tox-dev/tox/issues/672>`_)- avoid ``Requested Python version (X.Y) not installed`` stderr output when aPython environment is looked up using the ``py`` Python launcher on Windowsand the environment is not found installed on the system - byjurko-gospodnetic (`692 <https://github.com/tox-dev/tox/issues/692>`_)- Fixed an issue where invocation of tox from the Python package, whereinvocation errors (failed actions) occur results in a change in thesys.stdout stream encoding in Python 3.x. New behaviour is that sys.stdout isreset back to its original encoding after invocation errors - by tonybaloney(`723 <https://github.com/tox-dev/tox/issues/723>`_)- The reading of command output sometimes failed with ``IOError: [Errno 0]Error`` on Windows, this was fixed by using a simpler method to update theread buffers. - by fschulze (`727<https://github.com/tox-dev/tox/issues/727>`_)- (only affected rc releases) fix up tox.cmdline to be callable without args - bygaborbernat. (`773 <https://github.com/tox-dev/tox/issues/773>`_)- (only affected rc releases) Revert breaking change of tox.cmdline not callablewith no args - by gaborbernat. (`773 <https://github.com/tox-dev/tox/issues/773>`_)- (only affected rc releases) fix 755 by reverting the ``cmdline`` import to the oldlocation and changing the entry point instead - by fschulze(`755 <https://github.com/tox-dev/tox/issues/755>`_)Features^^^^^^^^- ``tox`` displays exit code together with ``InvocationError`` - by blueyedand ederag. (`290 <https://github.com/tox-dev/tox/issues/290>`_)- Hint for possible signal upon ``InvocationError``, on posix systems - byederag and asottile. (`766 <https://github.com/tox-dev/tox/issues/766>`_)- Add a ``-q`` option to progressively silence tox's output. For each time youspecify ``-q`` to tox, the output provided by tox reduces. This option allowsyou to see only your command output without the default verbosity of what toxis doing. This also counter-acts usage of ``-v``. For example, running ``tox-v -q ...`` will provide you with the default verbosity. ``tox -vv -q`` isequivalent to ``tox -v``. By sigmavirus24 (`256<https://github.com/tox-dev/tox/issues/256>`_)- add support for negated factor conditions, e.g. ``!dev: production_log`` - byjurko-gospodnetic (`292 <https://github.com/tox-dev/tox/issues/292>`_)- Headings like ``installed: <packages>`` will not be printed if there is nooutput to display after the :, unless verbosity is set. By cryvate (`601<https://github.com/tox-dev/tox/issues/601>`_)- Allow spaces in command line options to pip in deps. Where previously only``deps=-rreq.txt`` and ``deps=--requirement=req.txt`` worked, now also``deps=-r req.txt`` and ``deps=--requirement req.txt`` work - by cryvate(`668 <https://github.com/tox-dev/tox/issues/668>`_)- drop Python ``2.6`` and ``3.3`` support: ``setuptools`` dropped supportingthese, and as we depend on it we'll follow up with doing the same (use ``tox<= 2.9.1`` if you still need this support) - by gaborbernat (`679<https://github.com/tox-dev/tox/issues/679>`_)- Add tox_runenvreport as a possible plugin, allowing the overriding of thedefault behaviour to execute a command to get the installed packages within avirtual environment - by tonybaloney (`725<https://github.com/tox-dev/tox/issues/725>`_)- Forward ``PROCESSOR_ARCHITECTURE`` by default on Windows to fix``platform.machine()``. (`740 <https://github.com/tox-dev/tox/issues/740>`_)Documentation^^^^^^^^^^^^^- Change favicon to the vector beach ball - by hazalozturk(`748 <https://github.com/tox-dev/tox/issues/748>`_)- Change sphinx theme to alabaster and add logo/favicon - by hazalozturk(`639 <https://github.com/tox-dev/tox/issues/639>`_)Miscellaneous^^^^^^^^^^^^^- Running ``tox`` without a ``setup.py`` now has a more friendly error messageand gives troubleshooting suggestions - by Volcyy.(`331 <https://github.com/tox-dev/tox/issues/331>`_)- Fix pycodestyle (formerly pep8) errors E741 (ambiguous variable names, inthis case, 'l's) and remove ignore of this error in tox.ini - by cryvate(`663 <https://github.com/tox-dev/tox/issues/663>`_)- touched up ``interpreters.py`` code and added some missing tests for it - byjurko-gospodnetic (`708 <https://github.com/tox-dev/tox/issues/708>`_)- The ``PYTHONDONTWRITEBYTECODE`` environment variable is no longer unset - bystephenfin. (`744 <https://github.com/tox-dev/tox/issues/744>`_)