Fix UpdateNotCalled being an instance

CHANGES.rst

@@ -5,7 +5,8 @@
 4.1.1 (unreleased)
 ==================
 
-- Nothing changed yet.
+- Fixed UpdateNotCalled being an instance rather than an exception class
+  (https://github.com/zopefoundation/zope.contentprovider/issues/4).
 
 
 4.1.0 (2017-08-08)

src/zope/contentprovider/interfaces.py

@@ -29,10 +29,10 @@ class IUpdateNotCalled(zope.interface.common.interfaces.IRuntimeError):
     """
 
 class UpdateNotCalled(RuntimeError):
-    pass
-
-# Make it a singelton
-UpdateNotCalled = UpdateNotCalled('``update()`` was not called yet.')
+    def __init__(self, *args):
+        if not args:
+            args = ('``update()`` was not called yet.',)
+        super(UpdateNotCalled, self).__init__(*args)
 
 class IBeforeUpdateEvent(IObjectEvent):
 

src/zope/contentprovider/tests.py

@@ -20,6 +20,17 @@
 
 from zope.component import eventtesting
 from zope.testing import cleanup, renormalizing
+from zope.contentprovider.interfaces import UpdateNotCalled
+
+
+class TestExceptionHandling(unittest.TestCase):
+
+    def test(self):
+        try:
+            raise UpdateNotCalled
+        except UpdateNotCalled:
+            pass
+
 
 counter = 0
 mtime_func = None
@@ -62,14 +73,16 @@ def tearDown(test):
     global counter
     counter = 0
 
+
 def test_suite():
-    return unittest.TestSuite((
+    return unittest.TestSuite([
+        unittest.defaultTestLoader.loadTestsFromName(__name__),
         doctest.DocFileSuite(
             'README.rst',
             setUp=setUp, tearDown=tearDown,
-            optionflags=doctest.NORMALIZE_WHITESPACE|doctest.ELLIPSIS,
+            optionflags=doctest.NORMALIZE_WHITESPACE | doctest.ELLIPSIS,
             checker=checker,
             globs={'__file__': os.path.join(
                 os.path.dirname(__file__), 'README.rst')}
         ),
-    ))
+    ])