[parametrize] enforce explicit argnames declaration (#6330)

Every argname used in `parametrize` either must
be declared explicitly in the python test function, or via
`indirect` list

Fix #5712

AUTHORS

@@ -274,6 +274,7 @@ Vidar T. Fauske
 Virgil Dupras
 Vitaly Lashmanov
 Vlad Dragos
+Vladyslav Rachek
 Volodymyr Piskun
 Wei Lin
 Wil Cooley

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.

doc/en/example/parametrize.rst

@@ -398,6 +398,9 @@ The result of this test will be successful:
 
 .. regendoc:wipe
 
+Note, that each argument in `parametrize` list should be explicitly declared in corresponding
+python test function or via `indirect`.
+
 Parametrizing test methods through per-class configuration
 --------------------------------------------------------------
 

src/_pytest/fixtures.py

@@ -1,6 +1,5 @@
 import functools
 import inspect
-import itertools
 import sys
 import warnings
 from collections import defaultdict
@@ -1279,10 +1278,8 @@ class FixtureManager:
         else:
             argnames = ()
 
-        usefixtures = itertools.chain.from_iterable(
+        usefixtures = get_use_fixtures_for_node(node)
-            mark.args for mark in node.iter_markers(name="usefixtures")
+        initialnames = usefixtures + argnames
-        )
-        initialnames = tuple(usefixtures) + argnames
         fm = node.session._fixturemanager
         initialnames, names_closure, arg2fixturedefs = fm.getfixtureclosure(
             initialnames, node, ignore_args=self._get_direct_parametrize_args(node)
@@ -1479,3 +1476,12 @@ class FixtureManager:
         for fixturedef in fixturedefs:
             if nodes.ischildnode(fixturedef.baseid, nodeid):
                 yield fixturedef
+
+
+def get_use_fixtures_for_node(node) -> Tuple[str, ...]:
+    """Returns the names of all the usefixtures() marks on the given node"""
+    return tuple(
+        str(name)
+        for mark in node.iter_markers(name="usefixtures")
+        for name in mark.args
+    )

src/_pytest/python.py

@@ -955,6 +955,8 @@ class Metafunc:
 
         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
@@ -1105,6 +1107,37 @@ class Metafunc:
                         pytrace=False,
                     )
 
+    def _validate_explicit_parameters(self, argnames, indirect):
+        """
+        The argnames in *parametrize* should either be declared explicitly via
+        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
+        """
+        if isinstance(indirect, bool) and indirect is True:
+            return
+        parametrized_argnames = list()
+        funcargnames = _pytest.compat.getfuncargnames(self.function)
+        if isinstance(indirect, Sequence):
+            for arg in argnames:
+                if arg not in indirect:
+                    parametrized_argnames.append(arg)
+        elif indirect is False:
+            parametrized_argnames = argnames
+
+        usefixtures = fixtures.get_use_fixtures_for_node(self.definition)
+
+        for arg in parametrized_argnames:
+            if arg not in funcargnames and arg not in usefixtures:
+                func_name = self.function.__name__
+                msg = (
+                    'In function "{func_name}":\n'
+                    'Parameter "{arg}" should be declared explicitly via indirect or in function itself'
+                ).format(func_name=func_name, arg=arg)
+                fail(msg, pytrace=False)
+
 
 def _find_parametrized_scope(argnames, arg2fixturedefs, indirect):
     """Find the most appropriate scope for a parametrized call based on its arguments.

testing/python/collect.py

@@ -463,7 +463,7 @@ class TestFunction:
                return '3'
 
             @pytest.mark.parametrize('fix2', ['2'])
-            def test_it(fix1):
+            def test_it(fix1, fix2):
                assert fix1 == '21'
                assert not fix3_instantiated
         """

testing/python/metafunc.py

@@ -28,6 +28,9 @@ class TestMetafunc:
         class DefinitionMock(python.FunctionDefinition):
             obj = attr.ib()
 
+            def listchain(self):
+                return []
+
         names = fixtures.getfuncargnames(func)
         fixtureinfo = FixtureInfo(names)
         definition = DefinitionMock._create(func)
@@ -1877,3 +1880,51 @@ class TestMarkersWithParametrization:
                 "*= 6 passed in *",
             ]
         )
+
+    def test_parametrize_explicit_parameters_func(self, testdir):
+        testdir.makepyfile(
+            """
+            import pytest
+
+
+            @pytest.fixture
+            def fixture(arg):
+                return arg
+
+            @pytest.mark.parametrize("arg", ["baz"])
+            def test_without_arg(fixture):
+                assert "baz" == fixture
+        """
+        )
+        result = testdir.runpytest()
+        result.assert_outcomes(error=1)
+        result.stdout.fnmatch_lines(
+            [
+                '*In function "test_without_arg"*',
+                '*Parameter "arg" should be declared explicitly via indirect or in function itself*',
+            ]
+        )
+
+    def test_parametrize_explicit_parameters_method(self, testdir):
+        testdir.makepyfile(
+            """
+            import pytest
+
+            class Test:
+                @pytest.fixture
+                def test_fixture(self, argument):
+                    return argument
+
+                @pytest.mark.parametrize("argument", ["foobar"])
+                def test_without_argument(self, test_fixture):
+                    assert "foobar" == test_fixture
+        """
+        )
+        result = testdir.runpytest()
+        result.assert_outcomes(error=1)
+        result.stdout.fnmatch_lines(
+            [
+                '*In function "test_without_argument"*',
+                '*Parameter "argument" should be declared explicitly via indirect or in function itself*',
+            ]
+        )