fix bug: a false xfail expression would erranonously report XPASS on failures

--HG--
branch : trunk

_py/test/plugin/pytest_skipping.py

@@ -120,18 +120,20 @@ def pytest_runtest_setup(item):
 def pytest_runtest_makereport(__multicall__, item, call):
     if call.when != "call":
         return
-    if hasattr(item, 'obj'):
-        expr, result = evalexpression(item, 'xfail')
-        if result:
-            rep = __multicall__.execute()
-            if call.excinfo:
-                rep.skipped = True
-                rep.failed = rep.passed = False
-            else:
-                rep.skipped = rep.passed = False
-                rep.failed = True
-            rep.keywords['xfail'] = True # expr
-            return rep
+    expr, result = evalexpression(item, 'xfail')
+    rep = __multicall__.execute()
+    if result:
+        if call.excinfo:
+            rep.skipped = True
+            rep.failed = rep.passed = False
+        else:
+            rep.skipped = rep.passed = False
+            rep.failed = True
+        rep.keywords['xfail'] = expr 
+    else:
+        if 'xfail' in rep.keywords:
+            del rep.keywords['xfail']
+    return rep
 
 # called by terminalreporter progress reporting
 def pytest_report_teststatus(report):

testing/pytest/plugin/test_pytest_skipping.py

@@ -59,6 +59,20 @@ def test_xfail_at_module(testdir):
     ])
     assert result.ret == 0
 
+def test_xfail_evalfalse_but_fails(testdir):
+    p = testdir.makepyfile("""
+        import py
+        @py.test.mark.xfail('False')
+        def test_fail():
+            assert 0
+    """)
+    result = testdir.runpytest(p, '--report=xfailed')
+    extra = result.stdout.fnmatch_lines([
+        "*test_xfail_evalfalse_but_fails*:4*",
+        "*1 failed*"
+    ])
+    assert result.ret == 1
+
 def test_skipif_decorator(testdir):
     p = testdir.makepyfile("""
         import py