Show a better message when 'request' is used in parametrize

Fix pytest-dev#6183

changelog/6183.bugfix.rst

@@ -0,0 +1,2 @@
+Using ``request`` as a parameter name in ``@pytest.mark.parametrize`` now produces a more
+user-friendly error.

src/_pytest/python.py

@@ -977,6 +977,14 @@ def parametrize(self, argnames, argvalues, indirect=False, ids=None, scope=None)
         )
         del argvalues
 
+        if "request" in argnames:
+            # from _pytest.config import UsageError
+            # raise UsageError('foo')
+            fail(
+                "'request' is a reserved name and cannot be used in @pytest.mark.parametrize",
+                pytrace=False,
+            )
+
         if scope is None:
             scope = _find_parametrized_scope(argnames, self._arg2fixturedefs, indirect)
 

testing/python/metafunc.py

@@ -72,6 +72,19 @@ def func(x):
         ):
             metafunc.parametrize("x", [1], scope="doggy")
 
+    def test_parametrize_request_name(self, testdir):
+        """Show proper error  when 'request' is used as a parameter name in parametrize (#6183)"""
+
+        def func(request):
+            pass
+
+        metafunc = self.Metafunc(func)
+        with pytest.raises(
+            pytest.fail.Exception,
+            match=r"'request' is a reserved name and cannot be used in @pytest.mark.parametrize",
+        ):
+            metafunc.parametrize("request", [1])
+
     def test_find_parametrized_scope(self):
         """unittest for _find_parametrized_scope (#3941)"""
         from _pytest.python import _find_parametrized_scope