Paratrization overrides existing fixtures.

--HG--
branch : override-fixture-via-parametrization

_pytest/python.py

@@ -368,7 +368,6 @@ def add_funcarg_pseudo_fixture_def(collector, metafunc, fixturemanager):
     arg2fixturedefs = metafunc._arg2fixturedefs
     for param_index, callspec in enumerate(metafunc._calls):
         for argname, argvalue in callspec.funcargs.items():
-            assert argname not in arg2fixturedefs
             arg2params.setdefault(argname, []).append(argvalue)
             if argname not in arg2scope:
                 scopenum = callspec._arg2scopenum.get(argname, scopenum_function)
@@ -387,7 +386,6 @@ def add_funcarg_pseudo_fixture_def(collector, metafunc, fixturemanager):
         # to make sure we only ever create an according fixturedef on
         # a per-scope basis. We thus store and cache the fixturedef on the
         # node related to the scope.
-        assert argname not in arg2fixturedefs, (argname, arg2fixturedefs)
         scope = arg2scope[argname]
         node = None
         if scope != "function":

testing/python/collect.py

@@ -372,6 +372,24 @@ class TestFunction:
         rec.assertoutcome(passed=2)
 
 
+    def test_parametrize_overrides_fixture(self, testdir):
+        """Test parametrization when parameter overrides existing fixture with same name."""
+        testdir.makepyfile("""
+            import pytest
+
+            @pytest.fixture
+            def value():
+                return 'value'
+
+            @pytest.mark.parametrize('value',
+                                     ['overrided'])
+            def test_overrided_via_param(value):
+                assert value == 'overrided'
+        """)
+        rec = testdir.inline_run()
+        rec.assertoutcome(passed=1)
+
+
     def test_parametrize_with_mark(selfself, testdir):
         items = testdir.getitems("""
             import pytest