implement request object as per docs

--HG--
branch : trunk

py/test/pycollect.py

@@ -415,15 +415,30 @@ class Function(FunctionMixin, py.test.collect.Item):
         
 
 class FuncargRequest:
+    class Error(LookupError):
+        """ error on performing funcarg request. """ 
+        
     def __init__(self, pyfuncitem, argname):
         self.pyfuncitem = pyfuncitem
         self.argname = argname 
-        funcargname = "pytest_funcarg__" + str(argname) 
-        pm = self.pyfuncitem.config.pluginmanager 
+        self.function = pyfuncitem.obj
+        self.config = pyfuncitem.config
         extra = []
         current = pyfuncitem
         while not isinstance(current, Module):
             current = current.parent
             if isinstance(current, (Instance, Module)):
                 extra.insert(0, current.obj)
-        self._methods = pm.listattr(funcargname, extra=extra)
+        self._methods = self.pyfuncitem.config.pluginmanager.listattr(
+            "pytest_funcarg__" + str(argname), 
+            extra=extra,
+        )
+
+    def call_next_provider(self):
+        if not self._methods:
+            raise self.Error("no provider methods left")
+        nextmethod = self._methods.pop()
+        return nextmethod(request=self)
+
+    def addfinalizer(self, finalizer):
+        self.pyfuncitem.addfinalizer(finalizer)

py/test/testing/test_funcargs.py

@@ -84,6 +84,16 @@ class TestFuncargs:
         assert not modcol.config.pluginmanager.isregistered(modcol.obj)
 
 class TestRequest:
+    def test_request_attributes(self, testdir):
+        item = testdir.getitem("""
+            def pytest_funcarg__something(request): pass
+            def test_func(something): pass
+        """)
+        req = item.getrequest("other")
+        assert req.argname == "other"
+        assert req.function == item.obj 
+        assert req.config == item.config 
+        
     def test_request_contains_funcargs_methods(self, testdir):
         modcol = testdir.getmodulecol("""
             def pytest_funcarg__something(request):
@@ -101,3 +111,23 @@ class TestRequest:
         method1, method2 = methods 
         assert not hasattr(method1, 'im_self')
         assert method2.im_self is not None
+
+    def test_request_call_next_provider(self, testdir):
+        item = testdir.getitem("""
+            def pytest_funcarg__something(request): pass
+            def test_func(something): pass
+        """)
+        req = item.getrequest("something")
+        val = req.call_next_provider()
+        assert val is None
+        py.test.raises(req.Error, "req.call_next_provider()")
+
+    def test_request_addfinalizer(self, testdir):
+        item = testdir.getitem("""
+            def pytest_funcarg__something(request): pass
+            def test_func(something): pass
+        """)
+        req = item.getrequest("something")
+        l = [1]
+        req.addfinalizer(l.pop)
+        item.teardown()