[TIP] py.test-1.3.1: new py.test.xfail, --maxfail, better reporting, fixes

[holger krekel]

The pylib/py.test 1.3.1 release brings: 

- the new imperative ``py.test.xfail()`` helper in order to have a test or 
  setup function result in an "expected failure"
- a new option ``--maxfail=NUM`` to stop the test run after some failures
- markers/decorators are now applicable to test classes (>=Python2.6)
- improved reporting, shorter tracebacks in several cases
- some simplified internals, more compatibility with Jython and PyPy 
- bug fixes and various refinements

See the below CHANGELOG entry below for more details and
http://pylib.org/install.html for installation instructions. 

If you used older versions of py.test you should be able to upgrade 
to 1.3.1 without changes to your test source code.  

py.test is an automated testing tool working with Python2, Python3, 
Jython and PyPy versions on all major operating systems.  It
offers a no-boilerplate testing approach and has inspired other testing
tools and enhancements in the standard Python library for more than five
years.  It has a simple and extensive plugin architecture, configurable
reporting and provides unique ways to make it fit to your testing
process and needs.  

See http://pytest.org for more info.

cheers and have fun,

holger krekel

Changes between 1.3.0 and 1.3.1
==================================================

New features 
++++++++++++++++++

- issue91: introduce new py.test.xfail(reason) helper 
  to imperatively mark a test as expected to fail. Can 
  be used from within setup and test functions. This is
  useful especially for parametrized tests when certain 
  configurations are expected-to-fail.  In this case the
  declarative approach with the @py.test.mark.xfail cannot
  be used as it would mark all configurations as xfail. 

- issue102: introduce new --maxfail=NUM option to stop
  test runs after NUM failures.  This is a generalization
  of the '-x' or '--exitfirst' option which is now equivalent
  to '--maxfail=1'.  Both '-x' and '--maxfail' will 
  now also print a line near the end indicating the Interruption. 

- issue89: allow py.test.mark decorators to be used on classes
  (class decorators were introduced with python2.6) and 
  also allow to have multiple markers applied at class/module level
  by specifying a list. 

- improve and refine letter reporting in the progress bar:
  .  pass
  f  failed test
  s  skipped tests (reminder: use for dependency/platform mismatch only)
  x  xfailed test (test that was expected to fail)
  X  xpassed test (test that was expected to fail but passed)

  You can use any combination of 'fsxX' with the '-r' extended
  reporting option. The xfail/xpass results will show up as 
  skipped tests in the junitxml output - which also fixes 
  issue99.

- make py.test.cmdline.main() return the exitstatus instead of raising 
  SystemExit and also allow it to be called multiple times.  This of
  course requires that your application and tests are properly teared 
  down and don't have global state. 

Fixes / Maintenance 
++++++++++++++++++++++

- improved traceback presentation: 
  - improved and unified reporting for "--tb=short" option
  - Errors during test module imports are much shorter, (using --tb=short style)
  - raises shows shorter more relevant tracebacks
  - --fulltrace now more systematically makes traces longer / inhibits cutting

- improve support for raises and other dynamically compiled code by
  manipulating python's linecache.cache instead of the previous
  rather hacky way of creating custom code objects.  This makes 
  it seemlessly work on Jython and PyPy where it previously didn't.

- fix issue96: make capturing more resilient against Control-C 
  interruptions (involved somewhat substantial refactoring
  to the underlying capturing functionality to avoid race 
  conditions).

- fix chaining of conditional skipif/xfail decorators - so it works now 
  as expected to use multiple @py.test.mark.skipif(condition) decorators,
  including specific reporting which of the conditions lead to skipping. 

- fix issue95: late-import zlib so that it's not required 
  for general py.test startup. 

- fix issue94: make reporting more robust against bogus source code
  (and internally be more careful when presenting unexpected byte sequences)