remove pytest_namespace from _pytest.mark and fix latent pytest nesting bug

_pytest/mark.py

@@ -66,10 +66,8 @@ class MarkerError(Exception):
     """Error in use of a pytest marker/attribute."""
 
 
-
 def pytest_namespace():
     return {
-        'mark': MarkGenerator(),
         'param': ParameterSet.param,
     }
 
@@ -225,9 +223,13 @@ def matchkeyword(colitem, keywordexpr):
 
 
 def pytest_configure(config):
-    import pytest
+    config._old_mark_config = MARK_GEN._config
     if config.option.strict:
-        pytest.mark._config = config
+        MARK_GEN._config = config
+
+
+def pytest_unconfigure(config):
+    MARK_GEN._config = config._old_mark_config
 
 
 class MarkGenerator(object):
@@ -241,11 +243,13 @@ class MarkGenerator(object):
 
     will set a 'slowtest' :class:`MarkInfo` object
     on the ``test_function`` object. """
+    _config = None
+
 
     def __getattr__(self, name):
         if name[0] == "_":
             raise AttributeError("Marker name must NOT start with underscore")
-        if hasattr(self, '_config'):
+        if self._config is not None:
             self._check(name)
         return MarkDecorator(Mark(name, (), {}))
 
@@ -263,6 +267,7 @@ class MarkGenerator(object):
         if name not in self._markers:
             raise AttributeError("%r not a registered marker" % (name,))
 
+
 def istestfunc(func):
     return hasattr(func, "__call__") and \
         getattr(func, "__name__", "<lambda>") != "<lambda>"
@@ -384,3 +389,6 @@ class MarkInfo(object):
     def __iter__(self):
         """ yield MarkInfo objects each relating to a marking-call. """
         return imap(MarkInfo, self._marks)
+
+
+MARK_GEN = MarkGenerator()

pytest.py

@@ -20,6 +20,7 @@ __all__ = [
     'skip',
     'importorskip',
     'exit',
+    'mark',
 
 ]
 
@@ -41,6 +42,7 @@ from _pytest import __version__
 from _pytest.debugging import pytestPDB as __pytestPDB
 from _pytest.recwarn import warns, deprecated_call
 from _pytest.runner import fail, skip, importorskip, exit
+from _pytest.mark import MARK_GEN as mark
 set_trace = __pytestPDB.set_trace
 
 _preloadplugins() # to populate pytest.* namespace so help(pytest) works