Drop support for Python 2.7 up to 3.6.

setup.py

@@ -56,6 +56,7 @@ def read(*rnames):
       packages=find_packages('src'),
       package_dir={'': 'src'},
       namespace_packages=['z3c'],
+      python_requires='>=3.7',
       extras_require=dict(
           test=[
               'zope.browserpage',

src/z3c/__init__.py

@@ -1,7 +1 @@
-# this is a namespace package
-try:
-    import pkg_resources
-    pkg_resources.declare_namespace(__name__)
-except ImportError:
-    import pkgutil
-    __path__ = pkgutil.extend_path(__path__, __name__)
+__import__('pkg_resources').declare_namespace(__name__)

src/z3c/testing/directive.py

@@ -11,10 +11,7 @@
 # FOR A PARTICULAR PURPOSE.
 #
 ##############################################################################
-try:
-    from cStringIO import StringIO
-except ImportError:
-    from io import StringIO
+from io import StringIO
 
 import zope.component
 import zope.security

src/z3c/testing/generation.py

@@ -19,7 +19,7 @@
 #
 ###############################################################################
 
-class ContextStub(object):
+class ContextStub:
     """Stub for the context argument passed to evolve scripts.
 
     >>> from zope.app.zopeappgenerations import getRootFolder
@@ -29,7 +29,7 @@ class ContextStub(object):
 
     """
 
-    class ConnectionStub(object):
+    class ConnectionStub:
         def __init__(self, root_folder, db):
             self.root_folder = root_folder
             self.db = db

src/z3c/testing/layer.py

@@ -28,7 +28,7 @@
 from zope.site import hooks
 
 
-class BufferedDatabaseTestLayer(object):
+class BufferedDatabaseTestLayer:
     """A test layer which creates a filestorage database.
 
     The created database is later used without the need to run through the

src/z3c/testing/tests.py

@@ -53,7 +53,7 @@ def method(a1):
 
 
 @zope.interface.implementer(ISample)
-class Sample(object):
+class Sample:
     """Sample object."""
 
     @non_overridable
@@ -70,7 +70,7 @@ def getTestInterface(self):
         return ISample
 
 
-class ExamplePage(object):
+class ExamplePage:
 
     def __call__(self):
         return "Example succeeded."
@@ -79,7 +79,7 @@ def __call__(self):
 def test_suite():
     suite = unittest.TestSuite()
     # Unit Tests
-    suite.addTest(unittest.makeSuite(TestTestCase))
+    suite.addTest(unittest.defaultTestLoader.loadTestsFromTestCase(TestTestCase))
     # Functional Tests
     if HAVE_FTEST:
         suites = (