Prefer component (over factory) in the serialization of utility registrations

CHANGES.rst

@@ -4,7 +4,10 @@ Changelog
 3.0.2 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- Use ``component`` in the serialization of utility registrations
+  if the registered component is a "global object".
+  Fixes
+  `#6 <https://github.com/zopefoundation/Products.GenericSetup/issues/6>_`.
 
 
 3.0.1 (2023-03-03)

src/Products/GenericSetup/components.py

@@ -29,6 +29,7 @@
 from .interfaces import ISetupEnviron
 from .utils import XMLAdapterBase
 from .utils import _getDottedName
+from .utils import _isGlobalObject
 from .utils import _resolveDottedName
 
 
@@ -495,6 +496,8 @@ def _extractUtilities(self):
                         # This is a five.localsitemanager wrapped utility
                         factory = _getDottedName(type(aq_base(comp)))
                         child.setAttribute('factory', factory)
+                elif _isGlobalObject(comp):
+                    child.setAttribute('component', _getDottedName(comp))
                 else:
                     factory = _getDottedName(type(comp))
                     child.setAttribute('factory', factory)

src/Products/GenericSetup/tests/test_components.py

@@ -239,6 +239,20 @@ def getExcludedInterfaces(self):
 """
 
 
+_INTERFACE_COMPONENT = b"""\
+<?xml version="1.0" encoding="utf-8"?>
+<componentregistry>
+ <adapters/>
+ <subscribers/>
+ <utilities>
+  <utility name="test_interface"
+     component="Products.GenericSetup.tests.test_components.ITestInterface"
+     interface="Products.GenericSetup.tests.test_components.ITestInterfaceType"/>
+ </utilities>
+</componentregistry>
+"""
+
+
 class ComponentRegistryXMLAdapterTests(BodyAdapterTestCase, unittest.TestCase):
 
     layer = ExportImportZCMLLayer
@@ -434,6 +448,26 @@ def test_remove_components(self):
         util = queryUtility(IDummyInterface2, name='dummy tool name2')
         self.assertFalse(util is None)
 
+    def test_export_interface_component(self):
+        sm = self._obj
+        sm.registerUtility(ITestInterface,
+                           ITestInterfaceType,
+                           "test_interface")
+        context = DummySetupEnviron()
+        adapted = getMultiAdapter((sm, context), IBody)
+        body = adapted.body
+        self.assertEqual(body, _INTERFACE_COMPONENT)
+
+    def test_import_interface_component(self):
+        from ..components import importComponentRegistry
+        sm = self._obj
+        context = DummyImportContext(sm, False)
+        context._files['componentregistry.xml'] = _INTERFACE_COMPONENT
+        importComponentRegistry(context)
+        self.assertIs(
+            sm.queryUtility(ITestInterfaceType, name="test_interface"),
+            ITestInterface)
+
     def setUp(self):
         # Create and enable a local component registry
         site = Folder()
@@ -459,6 +493,14 @@ def tearDown(self):
                               name='dummy')
 
 
+class ITestInterface(Interface):
+    """interface registered as utility."""
+
+
+class ITestInterfaceType(Interface):
+    """interface provided by ``ITestInterface``."""
+
+
 if PersistentComponents is not None:
     def test_suite():
         # reimport to make sure tests are run from Products

src/Products/GenericSetup/utils.py

@@ -115,6 +115,15 @@ def _resolveDottedName(dotted):
         return
 
 
+def _isGlobalObject(obj):
+    """Is *obj* identified by a dotted name?"""
+    try:
+        dn = _getDottedName(obj)
+        return obj is _resolveDottedName(dn)
+    except Exception:
+        return False
+
+
 def _extractDocstring(func, default_title, default_description):
     try:
         doc = getdoc(func)