Add changelog, refactor code

Author: erheron

changelog/5712.feature.rst

@@ -0,0 +1,2 @@
+Now all arguments to ``@pytest.mark.parametrize`` need to be explicitly declared in the function signature or via ``indirect``.
+Previously it was possible to omit an argument if a fixture with the same name existed, which was just an accident of implementation and was not meant to be a part of the API.

src/_pytest/python.py

@@ -928,7 +928,7 @@ def parametrize(
         ids=None,
         scope=None,
         *,
-        _param_mark: Optional[Mark] = None
+        _param_mark: Optional[Mark] = None,
     ):
         """ Add new invocations to the underlying test function using the list
         of argvalues for the given argnames.  Parametrization is performed
@@ -998,10 +998,11 @@ def parametrize(
             scope = _find_parametrized_scope(argnames, self._arg2fixturedefs, indirect)
 
         self._validate_if_using_arg_names(argnames, indirect)
-        self._validate_explicit_parameters(argnames, indirect)
 
         arg_values_types = self._resolve_arg_value_types(argnames, indirect)
 
+        self._validate_explicit_parameters(argnames, indirect)
+
         # Use any already (possibly) generated ids with parametrize Marks.
         if _param_mark and _param_mark._param_ids_from:
             generated_ids = _param_mark._param_ids_from._param_ids_generated
@@ -1155,18 +1156,18 @@ def _validate_if_using_arg_names(self, argnames, indirect):
     def _validate_explicit_parameters(self, argnames, indirect):
         """
         The argnames in *parametrize* should either be declared explicitly via
-        indirect list or explicitly in the function
+        indirect list or in the function signature
 
         :param List[str] argnames: list of argument names passed to ``parametrize()``.
         :param indirect: same ``indirect`` parameter of ``parametrize()``.
         :raise ValueError: if validation fails
         """
         func_name = self.function.__name__
-        if type(indirect) is bool and indirect is True:
+        if isinstance(indirect, bool) and indirect is True:
             return
         parametrized_argnames = list()
         funcargnames = _pytest.compat.getfuncargnames(self.function)
-        if type(indirect) is list:
+        if isinstance(indirect, Sequence):
             for arg in argnames:
                 if arg not in indirect:
                     parametrized_argnames.append(arg)