implement pytest.param

this allows a clear addition of parameterization parameters that carry along marks
instead of nesting multiple mark objects and destroying the possibility of creating
function valued parameters,
it just folders everything together into one object carrfying parameters, and the marks.

_pytest/mark.py

@@ -6,17 +6,72 @@ from collections import namedtuple
 from operator import attrgetter
 from .compat import imap
 
+
 def alias(name):
     return property(attrgetter(name), doc='alias for ' + name)
 
 
+class ParameterSet(namedtuple('ParameterSet', 'values, marks, id')):
+    @classmethod
+    def param(cls, *values, **kw):
+        marks = kw.pop('marks', ())
+        if isinstance(marks, MarkDecorator):
+            marks = marks,
+        else:
+            assert isinstance(marks, (tuple, list, set))
+
+        def param_extract_id(id=None):
+            return id
+
+        id = param_extract_id(**kw)
+        return cls(values, marks, id)
+
+    @classmethod
+    def extract_from(cls, parameterset, legacy_force_tuple=False):
+        """
+        :param parameterset:
+            a legacy style parameterset that may or may not be a tuple,
+            and may or may not be wrapped into a mess of mark objects
+
+        :param legacy_force_tuple:
+            enforce tuple wrapping so single argument tuple values
+            don't get decomposed and break tests
+
+        """
+
+        if isinstance(parameterset, cls):
+            return parameterset
+        if not isinstance(parameterset, MarkDecorator) and legacy_force_tuple:
+            return cls.param(parameterset)
+
+        newmarks = []
+        argval = parameterset
+        while isinstance(argval, MarkDecorator):
+            newmarks.append(MarkDecorator(Mark(
+                argval.markname, argval.args[:-1], argval.kwargs)))
+            argval = argval.args[-1]
+        assert not isinstance(argval, ParameterSet)
+        if legacy_force_tuple:
+            argval = argval,
+
+        return cls(argval, marks=newmarks, id=None)
+
+    @property
+    def deprecated_arg_dict(self):
+        return dict((mark.name, mark) for mark in self.marks)
+
+
 class MarkerError(Exception):
 
     """Error in use of a pytest marker/attribute."""
 
 
+
 def pytest_namespace():
-    return {'mark': MarkGenerator()}
+    return {
+        'mark': MarkGenerator(),
+        'param': ParameterSet.param,
+    }
 
 
 def pytest_addoption(parser):
@@ -212,6 +267,7 @@ def istestfunc(func):
     return hasattr(func, "__call__") and \
         getattr(func, "__name__", "<lambda>") != "<lambda>"
 
+
 class MarkDecorator(object):
     """ A decorator for test functions and test classes.  When applied
     it will create :class:`MarkInfo` objects which may be
@@ -257,8 +313,11 @@ class MarkDecorator(object):
     def markname(self):
         return self.name # for backward-compat (2.4.1 had this attr)
 
+    def __eq__(self, other):
+        return self.mark == other.mark
+
     def __repr__(self):
-        return "<MarkDecorator %r>" % self.mark
+        return "<MarkDecorator %r>" % (self.mark,)
 
     def __call__(self, *args, **kwargs):
         """ if passed a single callable argument: decorate it with mark info.
@@ -291,19 +350,7 @@ class MarkDecorator(object):
         return self.__class__(self.mark.combined_with(mark))
 
 
-def extract_argvalue(maybe_marked_args):
-    # TODO: incorrect mark data, the old code wanst able to collect lists
-    # individual parametrized argument sets can be wrapped in a series
-    # of markers in which case we unwrap the values and apply the mark
-    # at Function init
-    newmarks = {}
-    argval = maybe_marked_args
-    while isinstance(argval, MarkDecorator):
-        newmark = MarkDecorator(Mark(
-            argval.markname, argval.args[:-1], argval.kwargs))
-        newmarks[newmark.name] = newmark
-        argval = argval.args[-1]
-    return argval, newmarks
+
 
 
 class Mark(namedtuple('Mark', 'name, args, kwargs')):