Remove pytest_funcarg__ prefix support for defining fixtures

Fix #4543

changelog/4543.removal.rst

@@ -0,0 +1,3 @@
+Remove support to define fixtures using the ``pytest_funcarg__`` prefix. Use the ``@pytest.fixture`` decorator instead.
+
+See our `docs <https://docs.pytest.org/en/latest/deprecations.html#pytest-funcarg-prefix>`__ on information on how to update your code.

doc/en/deprecations.rst

@@ -237,26 +237,6 @@ By passing a string, users expect that pytest will interpret that command-line u
 on (for example ``bash`` or ``Powershell``), but this is very hard/impossible to do in a portable way.
 
 
-``pytest_funcarg__`` prefix
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. deprecated:: 3.0
-
-In very early pytest versions fixtures could be defined using the ``pytest_funcarg__`` prefix:
-
-.. code-block:: python
-
-    def pytest_funcarg__data():
-        return SomeData()
-
-Switch over to the ``@pytest.fixture`` decorator:
-
-.. code-block:: python
-
-    @pytest.fixture
-    def data():
-        return SomeData()
-
 [pytest] section in setup.cfg files
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -295,6 +275,27 @@ collection.
 This issue should affect only advanced plugins who create new collection types, so if you see this warning
 message please contact the authors so they can change the code.
 
+``pytest_funcarg__`` prefix
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+*Removed in version 4.0.*
+
+In very early pytest versions fixtures could be defined using the ``pytest_funcarg__`` prefix:
+
+.. code-block:: python
+
+    def pytest_funcarg__data():
+        return SomeData()
+
+Switch over to the ``@pytest.fixture`` decorator:
+
+.. code-block:: python
+
+    @pytest.fixture
+    def data():
+        return SomeData()
+
+
 Metafunc.addcall
 ~~~~~~~~~~~~~~~~
 

src/_pytest/config/__init__.py

@@ -261,8 +261,8 @@ class PytestPluginManager(PluginManager):
         # (see issue #1073)
         if not name.startswith("pytest_"):
             return
-        # ignore some historic special names which can not be hooks anyway
+        # ignore names which can not be hooks
-        if name == "pytest_plugins" or name.startswith("pytest_funcarg__"):
+        if name == "pytest_plugins":
             return
 
         method = getattr(plugin, name)

src/_pytest/deprecated.py

@@ -24,12 +24,6 @@ MAIN_STR_ARGS = RemovedInPytest4Warning(
 
 YIELD_TESTS = "yield tests were removed in pytest 4.0 - {name} will be ignored"
 
-FUNCARG_PREFIX = UnformattedWarning(
-    RemovedInPytest4Warning,
-    '{name}: declaring fixtures using "pytest_funcarg__" prefix is deprecated '
-    "and scheduled to be removed in pytest 4.0.  "
-    "Please remove the prefix and use the @pytest.fixture decorator instead.",
-)
 
 FIXTURE_FUNCTION_CALL = UnformattedWarning(
     RemovedInPytest4Warning,

src/_pytest/fixtures.py

@@ -38,8 +38,6 @@ from _pytest.deprecated import FIXTURE_NAMED_REQUEST
 from _pytest.outcomes import fail
 from _pytest.outcomes import TEST_OUTCOME
 
-FIXTURE_MSG = 'fixtures cannot have "pytest_funcarg__" prefix and be decorated with @pytest.fixture:\n{}'
-
 
 @attr.s(frozen=True)
 class PseudoFixtureDef(object):
@@ -1117,7 +1115,6 @@ class FixtureManager(object):
     by a lookup of their FuncFixtureInfo.
     """
 
-    _argprefix = "pytest_funcarg__"
     FixtureLookupError = FixtureLookupError
     FixtureLookupErrorRepr = FixtureLookupErrorRepr
 
@@ -1255,8 +1252,6 @@ class FixtureManager(object):
         items[:] = reorder_items(items)
 
     def parsefactories(self, node_or_obj, nodeid=NOTSET, unittest=False):
-        from _pytest import deprecated
-
         if nodeid is not NOTSET:
             holderobj = node_or_obj
         else:
@@ -1272,31 +1267,13 @@ class FixtureManager(object):
             # access below can raise. safe_getatt() ignores such exceptions.
             obj = safe_getattr(holderobj, name, None)
             marker = getfixturemarker(obj)
-            # fixture functions have a pytest_funcarg__ prefix (pre-2.3 style)
+            if not isinstance(marker, FixtureFunctionMarker):
-            # or are "@pytest.fixture" marked
-            if marker is None:
-                if not name.startswith(self._argprefix):
-                    continue
-                if not callable(obj):
-                    continue
-                marker = defaultfuncargprefixmarker
-
-                filename, lineno = getfslineno(obj)
-                warnings.warn_explicit(
-                    deprecated.FUNCARG_PREFIX.format(name=name),
-                    category=None,
-                    filename=str(filename),
-                    lineno=lineno + 1,
-                )
-                name = name[len(self._argprefix) :]
-            elif not isinstance(marker, FixtureFunctionMarker):
                 # magic globals  with __getattr__ might have got us a wrong
                 # fixture attribute
                 continue
-            else:
+
-                if marker.name:
+            if marker.name:
-                    name = marker.name
+                name = marker.name
-                assert not name.startswith(self._argprefix), FIXTURE_MSG.format(name)
 
             # during fixture definition we wrap the original fixture function
             # to issue a warning if called directly, so here we unwrap it in order to not emit the warning

testing/deprecated_test.py

@@ -10,28 +10,6 @@ from _pytest.warnings import SHOW_PYTEST_WARNINGS_ARG
 pytestmark = pytest.mark.pytester_example_path("deprecated")
 
 
-def test_funcarg_prefix_deprecation(testdir):
-    testdir.makepyfile(
-        """
-        def pytest_funcarg__value():
-            return 10
-
-        def test_funcarg_prefix(value):
-            assert value == 10
-    """
-    )
-    result = testdir.runpytest("-ra", SHOW_PYTEST_WARNINGS_ARG)
-    result.stdout.fnmatch_lines(
-        [
-            (
-                "*test_funcarg_prefix_deprecation.py:1: *pytest_funcarg__value: "
-                'declaring fixtures using "pytest_funcarg__" prefix is deprecated*'
-            ),
-            "*1 passed*",
-        ]
-    )
-
-
 @pytest.mark.filterwarnings("default")
 def test_pytest_setup_cfg_deprecated(testdir):
     testdir.makefile(

testing/python/fixture.py

@@ -627,25 +627,6 @@ class TestRequestBasic(object):
         print(ss.stack)
         assert teardownlist == [1]
 
-    def test_mark_as_fixture_with_prefix_and_decorator_fails(self, testdir):
-        testdir.makeconftest(
-            """
-            import pytest
-
-            @pytest.fixture
-            def pytest_funcarg__marked_with_prefix_and_decorator():
-                pass
-        """
-        )
-        result = testdir.runpytest_subprocess()
-        assert result.ret != 0
-        result.stdout.fnmatch_lines(
-            [
-                "*AssertionError: fixtures cannot have*@pytest.fixture*",
-                "*pytest_funcarg__marked_with_prefix_and_decorator*",
-            ]
-        )
-
     def test_request_addfinalizer_failing_setup(self, testdir):
         testdir.makepyfile(
             """