allow registration of "funcarg" marked factories

_pytest/main.py

@@ -463,10 +463,19 @@ class FuncargManager:
         self._holderobjseen.add(holderobj)
         for name in dir(holderobj):
             #print "check", holderobj, name
-            if name.startswith(self._argprefix):
-                fname = name[len(self._argprefix):]
-                faclist = self.arg2facspec.setdefault(fname, [])
             obj = getattr(holderobj, name)
+            # funcarg factories either have a pytest_funcarg__ prefix
+            # or are "funcarg" marked
+            if hasattr(obj, "funcarg"):
+                if name.startswith(self._argprefix):
+                    argname = name[len(self._argprefix):]
+                else:
+                    argname = name
+            elif name.startswith(self._argprefix):
+                argname = name[len(self._argprefix):]
+            else:
+                continue
+            faclist = self.arg2facspec.setdefault(argname, [])
             faclist.append((nodeid, obj))
 
     def getfactorylist(self, argname, nodeid, function, raising=True):

testing/test_python.py

@@ -1805,3 +1805,25 @@ class TestFuncargMarker:
             "*ScopeMismatch*You tried*function*from*session*",
         ])
 
+    def test_register_only_with_mark(self, testdir):
+        testdir.makeconftest("""
+            import pytest
+            finalized = []
+            created = []
+            @pytest.mark.funcarg
+            def arg(request):
+                return 1
+        """)
+        testdir.makepyfile(
+            test_mod1="""
+                import pytest
+                @pytest.mark.funcarg
+                def arg(request):
+                    return request.getfuncargvalue("arg") + 1
+                def test_1(arg):
+                    assert arg == 2
+            """)
+        reprec = testdir.inline_run()
+        reprec.assertoutcome(passed=1)
+
+