runzeo clears socket files no matter what type of string address is

Fixes #90

Also remove an unused and duplicate import from that file and the
redundant `test_suite` declaration from the test file. There was also
a duplicate method definition in the test file that was removed.

CHANGES.rst

@@ -8,6 +8,8 @@ Changelog
   new-style on Python 3). This improves performance on PyPy. See
   `issue 86 <<https://github.com/zopefoundation/ZEO/pull/86>`_.
 
+- Fixed removing UNIX socket files under Python 2 with ZConfig 3.2.0.
+  See `issue 90 <https://github.com/zopefoundation/ZEO/issues/90>`_.
 
 5.1.0 (2017-04-03)
 ------------------

src/ZEO/runzeo.py

@@ -29,19 +29,17 @@ Options:
 Unless -C is specified, -a and -f are required.
 """
 from __future__ import print_function
-from __future__ import print_function
 
 # The code here is designed to be reused by other, similar servers.
-# For the forseeable future, it must work under Python 2.1 as well as
-# 2.2 and above.
 
-import asyncore
 import os
 import sys
 import signal
 import socket
 import logging
 
+import six
+
 import ZConfig.datatypes
 from zdaemon.zdoptions import ZDOptions
 
@@ -193,11 +191,12 @@ class ZEOServer(object):
             return 1
 
     def clear_socket(self):
-        if isinstance(self.options.address, type("")):
+        if isinstance(self.options.address, six.string_types):
             try:
                 os.unlink(self.options.address)
             except os.error:
                 pass
+            return True
 
     def open_storages(self):
         self.storages = {}

src/ZEO/tests/testZEOServer.py

-#
-# Fix AttributeError: 'ZEOServer' object has no attribute 'server' in
-# ZEOServer.main
-#
 import unittest
 
 from ZEO.runzeo import ZEOServer
@@ -55,9 +51,6 @@ class TestZEOServer(ZEOServer):
         self.called.append("close_server")
         ZEOServer.close_server(self)
 
-    def clear_socket(self):
-        self.called.append("clear_socket")
-
     def remove_pidfile(self):
         self.called.append("remove_pidfile")
 
@@ -65,6 +58,10 @@ class TestZEOServer(ZEOServer):
 class AttributeErrorTests(unittest.TestCase):
 
     def testFailCreateServer(self):
+        #
+        # Fix AttributeError: 'ZEOServer' object has no attribute
+        # 'server' in ZEOServer.main
+        #
         # Demonstrate the AttributeError
         zeo = TestZEOServer(fail_create_server=True)
         self.assertRaises(RuntimeError, zeo.main)
@@ -138,8 +135,18 @@ class CloseServerTests(unittest.TestCase):
         self.assertEqual(zeo.server, None)
 
 
-def test_suite():
-    suite = unittest.TestSuite()
-    suite.addTest(unittest.makeSuite(AttributeErrorTests))
-    suite.addTest(unittest.makeSuite(CloseServerTests))
-    return suite
+class TestZEOServerSocket(unittest.TestCase):
+
+    def test_clear_with_native_str(self):
+        class Options(object):
+            address = "a str that does not exist"
+
+        server = ZEOServer(Options())
+        self.assertTrue(server.clear_socket())
+
+    def test_clear_with_unicode_str(self):
+        class Options(object):
+            address = u"a str that does not exist"
+
+        server = ZEOServer(Options())
+        self.assertTrue(server.clear_socket())