Refactor `test_attrgetter_using` (#11293)

Co-authored-by: Adam Turner <9087854+aa-turner@users.noreply.github.com>

tests/test_ext_autodoc.py

@@ -403,42 +403,40 @@ def test_new_documenter(app):
     ]
 
 
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_attrgetter_using(app):
-    from target import Class
-    from target.inheritance import Derived
-
     directive = make_directive_bridge(app.env)
+    directive.genopt['members'] = ALL
 
-    def assert_getter_works(objtype, name, obj, attrs=[], **kw):
-        getattr_spy = []
-
-        def special_getattr(obj, name, *defargs):
-            if name in attrs:
-                getattr_spy.append((obj, name))
-                return None
-            return getattr(obj, name, *defargs)
-        app.add_autodoc_attrgetter(type, special_getattr)
-
-        del getattr_spy[:]
-        inst = app.registry.documenters[objtype](directive, name)
-        inst.generate(**kw)
-
-        hooked_members = [s[1] for s in getattr_spy]
-        documented_members = [s[1] for s in processed_signatures]
-        for attr in attrs:
-            fullname = '.'.join((name, attr))
-            assert attr in hooked_members
-            assert fullname not in documented_members, \
-                '%r was not hooked by special_attrgetter function' % fullname
-
+    directive.genopt['inherited_members'] = False
     with catch_warnings(record=True):
-        directive.genopt['members'] = ALL
-        directive.genopt['inherited_members'] = False
-        print(directive.genopt)
-        assert_getter_works('class', 'target.Class', Class, ['meth'])
+        _assert_getter_works(app, directive, 'class', 'target.Class', ['meth'])
 
-        directive.genopt['inherited_members'] = True
-        assert_getter_works('class', 'target.inheritance.Derived', Derived, ['inheritedmeth'])
+    directive.genopt['inherited_members'] = True
+    with catch_warnings(record=True):
+        _assert_getter_works(app, directive, 'class', 'target.inheritance.Derived', ['inheritedmeth'])
+
+
+def _assert_getter_works(app, directive, objtype, name, attrs=(), **kw):
+    getattr_spy = []
+
+    def _special_getattr(obj, attr_name, *defargs):
+        if attr_name in attrs:
+            getattr_spy.append((obj, attr_name))
+            return None
+        return getattr(obj, attr_name, *defargs)
+
+    app.add_autodoc_attrgetter(type, _special_getattr)
+
+    getattr_spy.clear()
+    app.registry.documenters[objtype](directive, name).generate(**kw)
+
+    hooked_members = {s[1] for s in getattr_spy}
+    documented_members = {s[1] for s in processed_signatures}
+    for attr in attrs:
+        fullname = '.'.join((name, attr))
+        assert attr in hooked_members
+        assert fullname not in documented_members, f'{fullname!r} not intercepted'
 
 
 @pytest.mark.sphinx('html', testroot='ext-autodoc')