new --runxfail option to ignore xfail markers on functions

--HG--
branch : trunk

CHANGELOG

@@ -14,9 +14,10 @@ Changes between 1.2.1 and 1.3.0 (release pending)
 - new pytest_pycollect_makemodule(path, parent) hook for
   allowing customization of the Module collection object for a 
   matching test module. 
-- extend py.test.mark.xfail to accept two more keyword arg parameters:
+- extend and refine xfail mechanism: 
-  ``xfail(run=False)`` will not run the decorated test 
+  ``@py.test.mark.xfail(run=False)`` do not run the decorated test
-  ``xfail(reason="...")`` will print the reason string when reporting 
+  ``@py.test.mark.xfail(reason="...")`` prints the reason string in xfail summaries
+  specifiying ``--runxfail`` on command line virtually ignores xfail markers
 - expose (previously internal) commonly useful methods: 
   py.io.get_terminal_with() -> return terminal width
   py.io.ansi_print(...) -> print colored/bold text on linux/win32

py/_plugin/pytest_skipping.py

@@ -126,6 +126,12 @@ within test or setup code.  Example::
 
 import py
 
+def pytest_addoption(parser):
+    group = parser.getgroup("general")
+    group.addoption('--runxfail', 
+           action="store_true", dest="runxfail", default=False,
+           help="run tests even if they are marked xfail")
+
 class MarkEvaluator:
     def __init__(self, item, name):
         self.item = item
@@ -172,6 +178,7 @@ def pytest_runtest_setup(item):
     if evalskip.istrue():
         py.test.skip(evalskip.getexplanation())
     item._evalxfail = MarkEvaluator(item, 'xfail')
+    if not item.config.getvalue("runxfail"):
         if item._evalxfail.istrue():
             if not item._evalxfail.get('run', True):
                 py.test.skip("xfail")
@@ -192,7 +199,7 @@ def pytest_runtest_makereport(__multicall__, item, call):
         return rep
     elif call.when == "call":
         rep = __multicall__.execute()
-        if evalxfail.istrue():
+        if not item.config.getvalue("runxfail") and evalxfail.istrue():
             if call.excinfo:
                 rep.skipped = True
                 rep.failed = rep.passed = False

testing/plugin/test_pytest_skipping.py

@@ -96,6 +96,21 @@ class TestXFail:
         expl = callreport.keywords['xfail']
         assert expl == "condition: True"
 
+    def test_xfail_run_anyway(self, testdir):
+        testdir.makepyfile("""
+            import py 
+            @py.test.mark.xfail
+            def test_func(): 
+                assert 0
+        """)
+        result = testdir.runpytest("--runxfail")
+        assert result.ret == 1
+        result.stdout.fnmatch_lines([
+            "*def test_func():*",
+            "*assert 0*",
+            "*1 failed*",
+        ])
+
     def test_xfail_evalfalse_but_fails(self, testdir):
         item = testdir.getitem("""
             import py