Replace yield_fixture -> fixture in internal code

`yield_fixture` is a deprecated alias to `fixture`.

src/_pytest/fixtures.py

@@ -924,9 +924,7 @@ def _teardown_yield_fixture(fixturefunc, it) -> None:
     except StopIteration:
         pass
     else:
-        fail_fixturefunc(
-            fixturefunc, "yield_fixture function has more than one 'yield'"
-        )
+        fail_fixturefunc(fixturefunc, "fixture function has more than one 'yield'")
 
 
 def _eval_scope_callable(

src/_pytest/recwarn.py

@@ -13,14 +13,14 @@ from typing import Union
 
 from _pytest.compat import overload
 from _pytest.compat import TYPE_CHECKING
-from _pytest.fixtures import yield_fixture
+from _pytest.fixtures import fixture
 from _pytest.outcomes import fail
 
 if TYPE_CHECKING:
     from typing import Type
 
 
-@yield_fixture
+@fixture
 def recwarn():
     """Return a :class:`WarningsRecorder` instance that records all warnings emitted by test functions.
 

testing/example_scripts/issue_519.py

@@ -33,13 +33,13 @@ def checked_order():
     ]
 
 
-@pytest.yield_fixture(scope="module")
+@pytest.fixture(scope="module")
 def fix1(request, arg1, checked_order):
     checked_order.append((request.node.name, "fix1", arg1))
     yield "fix1-" + arg1
 
 
-@pytest.yield_fixture(scope="function")
+@pytest.fixture(scope="function")
 def fix2(request, fix1, arg2, checked_order):
     checked_order.append((request.node.name, "fix2", arg2))
     yield "fix2-" + arg2 + fix1

testing/python/fixtures.py

@@ -1315,7 +1315,7 @@ class TestFixtureUsages:
 
             DB_INITIALIZED = None
 
-            @pytest.yield_fixture(scope="session", autouse=True)
+            @pytest.fixture(scope="session", autouse=True)
             def db():
                 global DB_INITIALIZED
                 DB_INITIALIZED = True
@@ -2960,8 +2960,7 @@ class TestFixtureMarker:
             """
             import pytest
 
-            @pytest.yield_fixture(params=[object(), object()],
-                                  ids=['alpha', 'beta'])
+            @pytest.fixture(params=[object(), object()], ids=['alpha', 'beta'])
             def fix(request):
                  yield request.param
 

testing/test_doctest.py

@@ -1176,7 +1176,7 @@ class TestDoctestAutoUseFixtures:
             import pytest
             import sys
 
-            @pytest.yield_fixture(autouse=True, scope='session')
+            @pytest.fixture(autouse=True, scope='session')
             def myfixture():
                 assert not hasattr(sys, 'pytest_session_data')
                 sys.pytest_session_data = 1

testing/test_pathlib.py

@@ -91,7 +91,7 @@ class TestImportPath:
     Having our own pyimport-like function is inline with removing py.path dependency in the future.
     """
 
-    @pytest.yield_fixture(scope="session")
+    @pytest.fixture(scope="session")
     def path1(self, tmpdir_factory):
         path = tmpdir_factory.mktemp("path")
         self.setuptestfs(path)