port avocado.plugins.xunit to Python 3

At least, selftests.unit.test_xunit passes.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

avocado/plugins/xunit.py

@@ -117,7 +117,7 @@ class XUnitResult(Result):
         content = self._render(result)
         if getattr(job.args, 'xunit_job_result', 'off') == 'on':
             xunit_path = os.path.join(job.logdir, 'results.xml')
-            with open(xunit_path, 'w') as xunit_file:
+            with open(xunit_path, 'wb') as xunit_file:
                 xunit_file.write(content)
 
         xunit_path = getattr(job.args, 'xunit_output', 'None')
@@ -125,7 +125,7 @@ class XUnitResult(Result):
             if xunit_path == '-':
                 LOG_UI.debug(content)
             else:
-                with open(xunit_path, 'w') as xunit_file:
+                with open(xunit_path, 'wb') as xunit_file:
                     xunit_file.write(content)
 
 

selftests/unit/test_xunit.py

@@ -4,9 +4,13 @@ import shutil
 import tempfile
 import unittest
 from lxml import etree
-from StringIO import StringIO
 from xml.dom import minidom
 
+try:
+    from io import BytesIO
+except:
+    from BytesIO import BytesIO
+
 from avocado import Test
 from avocado.core import job
 from avocado.core.result import Result
@@ -57,7 +61,7 @@ class xUnitSucceedTest(unittest.TestCase):
         self.test_result.end_tests()
         xunit_result = xunit.XUnitResult()
         xunit_result.render(self.test_result, self.job)
-        with open(self.job.args.xunit_output) as fp:
+        with open(self.job.args.xunit_output, 'rb') as fp:
             xml = fp.read()
         try:
             dom = minidom.parseString(xml)
@@ -69,7 +73,7 @@ class xUnitSucceedTest(unittest.TestCase):
 
         with open(self.junit, 'r') as f:
             xmlschema = etree.XMLSchema(etree.parse(f))
-        self.assertTrue(xmlschema.validate(etree.parse(StringIO(xml))),
+        self.assertTrue(xmlschema.validate(etree.parse(BytesIO(xml))),
                         "Failed to validate against %s, content:\n%s" %
                         (self.junit, xml))