Add pytest.fixture(indirect=...) argument

closes #10101

AUTHORS

@@ -238,6 +238,7 @@ Michael Goerz
 Michael Krebs
 Michael Seifert
 Michal Wajszczuk
+Michał Lowas-Rzechonek
 Michał Zięba
 Mihai Capotă
 Mike Hoyle (hoylemd)

changelog/10101.feature.rst

@@ -0,0 +1,2 @@
+Add an optional ``indirect`` argument for ``pytest.fixture`` to make all
+parametrizations of that fixture indirect by default.

doc/en/example/parametrize.rst

@@ -372,6 +372,24 @@ test:
 This can be used, for example, to do more expensive setup at test run time in
 the fixture, rather than having to run those setup steps at collection time.
 
+It's also possible to configure this on the fixture level, making all tests
+using that fixture indirectly parametrized by default:
+
+.. code-block:: python
+
+    import pytest
+
+
+    @pytest.fixture(indirect=True)
+    def fixt(request):
+        return request.param * 3
+
+
+    @pytest.mark.parametrize("fixt", ["a", "b"])
+    def test_indirect(fixt):
+        assert len(fixt) == 3
+
+
 .. regendoc:wipe
 
 Apply indirect on particular arguments

src/_pytest/fixtures.py

@@ -212,6 +212,7 @@ def add_funcarg_pseudo_fixture_def(
                 func=get_direct_param_fixture_func,
                 scope=arg2scope[argname],
                 params=valuelist,
+                indirect=False,
                 unittest=False,
                 ids=None,
             )
@@ -943,6 +944,7 @@ class FixtureDef(Generic[FixtureValue]):
         func: "_FixtureFunc[FixtureValue]",
         scope: Union[Scope, "_ScopeName", Callable[[str, Config], "_ScopeName"], None],
         params: Optional[Sequence[object]],
+        indirect: bool = False,
         unittest: bool = False,
         ids: Optional[
             Union[Tuple[Optional[object], ...], Callable[[Any], Optional[object]]]
@@ -987,6 +989,8 @@ class FixtureDef(Generic[FixtureValue]):
         # assign to the parameter values, or a callable to generate an ID given
         # a parameter value.
         self.ids = ids
+        # Whether the fixture should be always indirectly parametrized
+        self.indirect = indirect
         # The names requested by the fixtures.
         self.argnames = getfuncargnames(func, name=argname, is_method=unittest)
         # Whether the fixture was collected from a unittest TestCase class.
@@ -1174,6 +1178,7 @@ class FixtureFunctionMarker:
         converter=_ensure_immutable_ids,
     )
     name: Optional[str] = None
+    indirect: bool = False
 
     def __call__(self, function: FixtureFunction) -> FixtureFunction:
         if inspect.isclass(function):
@@ -1241,6 +1246,7 @@ def fixture(
         Union[Sequence[Optional[object]], Callable[[Any], Optional[object]]]
     ] = None,
     name: Optional[str] = None,
+    indirect: bool = False,
 ) -> Union[FixtureFunctionMarker, FixtureFunction]:
     """Decorator to mark a fixture factory function.
 
@@ -1298,6 +1304,7 @@ def fixture(
         autouse=autouse,
         ids=ids,
         name=name,
+        indirect=indirect,
     )
 
     # Direct decoration.
@@ -1417,7 +1424,11 @@ class FixtureManager:
                 p_argnames, _ = ParameterSet._parse_parametrize_args(
                     *marker.args, **marker.kwargs
                 )
-                parametrize_argnames.extend(p_argnames)
+                for argname in p_argnames:
+                    fixturedefs = self.getfixturedefs(argname, node.nodeid) or []
+                    if any(f.indirect for f in fixturedefs):
+                        continue
+                    parametrize_argnames.append(argname)
 
         return parametrize_argnames
 
@@ -1614,10 +1625,14 @@ class FixtureManager:
                 func=obj,
                 scope=marker.scope,
                 params=marker.params,
+                indirect=marker.indirect,
                 unittest=unittest,
                 ids=marker.ids,
             )
 
+            if marker.indirect:
+                fixture_def.params = fixture_def.params or []
+
             faclist = self._arg2fixturedefs.setdefault(name, [])
             if fixture_def.has_location:
                 faclist.append(fixture_def)

src/_pytest/python.py

@@ -1194,8 +1194,8 @@ class Metafunc:
         #: Underlying Python test function.
         self.function = definition.obj
 
-        #: Set of fixture names required by the test function.
+        #: Set of fixtures required by the test function
-        self.fixturenames = fixtureinfo.names_closure
+        self.fixtureinfo = fixtureinfo
 
         #: Class object where the test function is defined in or ``None``.
         self.cls = cls
@@ -1205,6 +1205,10 @@ class Metafunc:
         # Result of parametrize().
         self._calls: List[CallSpec2] = []
 
+    @property
+    def fixturenames(self):
+        return self.fixtureinfo.names_closure
+
     def parametrize(
         self,
         argnames: Union[str, List[str], Tuple[str, ...]],
@@ -1300,8 +1304,23 @@ class Metafunc:
         else:
             scope_ = _find_parametrized_scope(argnames, self._arg2fixturedefs, indirect)
 
+        if not isinstance(indirect, (bool, Sequence)):
+            fail(
+                "In {func}: expected Sequence or boolean for indirect, got {type}".format(
+                    type=type(indirect).__name__, func=self.function.__name__
+                ),
+                pytrace=False,
+            )
+
         self._validate_if_using_arg_names(argnames, indirect)
 
+        if indirect is not True:  # False, or a list
+            indirect = list(indirect or [])
+            for argname in argnames:
+                fixturedefs = self.fixtureinfo.name2fixturedefs.get(argname, [])
+                if any(f.indirect for f in fixturedefs):
+                    indirect.append(argname)
+
         arg_values_types = self._resolve_arg_value_types(argnames, indirect)
 
         # Use any already (possibly) generated ids with parametrize Marks.
@@ -1435,13 +1454,7 @@ class Metafunc:
                         pytrace=False,
                     )
                 valtypes[arg] = "params"
-        else:
+
-            fail(
-                "In {func}: expected Sequence or boolean for indirect, got {type}".format(
-                    type=type(indirect).__name__, func=self.function.__name__
-                ),
-                pytrace=False,
-            )
         return valtypes
 
     def _validate_if_using_arg_names(

testing/python/fixtures.py

@@ -4468,3 +4468,105 @@ def test_yield_fixture_with_no_value(pytester: Pytester) -> None:
     result.assert_outcomes(errors=1)
     result.stdout.fnmatch_lines([expected])
     assert result.ret == ExitCode.TESTS_FAILED
+
+
+def test_fixture_indirect(pytester: Pytester) -> None:
+    pytester.makeconftest(
+        """
+        import pytest
+        @pytest.fixture(indirect=True)
+        def indirect_sum(request):
+            return sum(request.param)
+
+        @pytest.fixture
+        def indirect_reversed(request):
+            return list(reversed(request.param))
+        """
+    )
+
+    pytester.makepyfile(
+        """
+        import pytest
+        @pytest.mark.parametrize("indirect_sum, indirect_reversed, direct_list",
+            [
+                ([1,2,3], [1,2,3], [1,2,3])
+            ],
+            indirect=["indirect_reversed"]
+        )
+        def test_indirect_sum(indirect_sum, indirect_reversed, direct_list):
+            assert indirect_sum == 6
+            assert indirect_reversed == [3, 2, 1]
+            assert direct_list == [1, 2, 3]
+        """
+    )
+    result = pytester.runpytest()
+    result.assert_outcomes(passed=1)
+
+
+def test_fixture_indirect_always(pytester: Pytester) -> None:
+    pytester.makeconftest(
+        """
+        import pytest
+        @pytest.fixture(indirect=True)
+        def indirect_sum(request):
+            return sum(request.param)
+        """
+    )
+
+    pytester.makepyfile(
+        """
+        import pytest
+        @pytest.mark.parametrize("indirect_sum",
+            [
+                ([1,2,3])
+            ],
+            indirect=[]
+        )
+        def test_indirect_sum(indirect_sum):
+            assert indirect_sum == 6
+        """
+    )
+    result = pytester.runpytest()
+    result.assert_outcomes(passed=1)
+
+
+def test_fixture_indirect_no_params(pytester: Pytester) -> None:
+    pytester.makeconftest(
+        """
+        import pytest
+        @pytest.fixture(indirect=True)
+        def indirect_skip(request):
+            pass
+        """
+    )
+
+    pytester.makepyfile(
+        """
+        import pytest
+        def test_indirect_skip(indirect_skip):
+            pass
+        """
+    )
+    result = pytester.runpytest()
+    result.assert_outcomes(skipped=1)
+
+
+def test_fixture_indirect_default_params(pytester: Pytester) -> None:
+    pytester.makeconftest(
+        """
+        import pytest
+        @pytest.fixture(indirect=True, params=[1])
+        def indirect_default(request):
+            return request.param
+        """
+    )
+
+    pytester.makepyfile(
+        """
+        import pytest
+        def test_indirect_sum(indirect_default):
+            assert indirect_default == 1
+        """
+    )
+    result = pytester.runpytest()
+    result.assert_outcomes(passed=1)

testing/python/metafunc.py

@@ -22,6 +22,7 @@ from _pytest import python
 from _pytest.compat import _format_args
 from _pytest.compat import getfuncargnames
 from _pytest.compat import NOTSET
+from _pytest.fixtures import FixtureDef
 from _pytest.outcomes import fail
 from _pytest.pytester import Pytester
 from _pytest.python import IdMaker
@@ -34,7 +35,7 @@ class TestMetafunc:
         # on the funcarg level, so we don't need a full blown
         # initialization.
         class FuncFixtureInfoMock:
-            name2fixturedefs = None
+            name2fixturedefs: Dict[str, Sequence["FixtureDef[Any]"]] = {}
 
             def __init__(self, names):
                 self.names_closure = names