xmlutil: add a diff() helper

And centralize all the scattered difflib calls we have

Signed-off-by: Cole Robinson <crobinso@redhat.com>

tests/utils.py

@@ -3,7 +3,6 @@
 # This work is licensed under the GNU GPLv2 or later.
 # See the COPYING file in the top-level directory.
 
-import difflib
 import os
 import sys
 import unittest
@@ -11,8 +10,9 @@ import unittest
 import libvirt
 
 import virtinst
-from virtinst import cli
 import virtinst.uri
+from virtinst import cli
+from virtinst import xmlutil
 
 
 # pylint: disable=protected-access
@@ -231,10 +231,8 @@ def diff_compare(actual_out, filename=None, expect_out=None):
             open(filename, "w").write(actual_out)
         expect_out = open(filename).read()
 
-    diff = "".join(difflib.unified_diff(expect_out.splitlines(1),
-                                        actual_out.splitlines(1),
-                                        fromfile=filename or '',
-                                        tofile="Generated Output"))
+    diff = xmlutil.diff(expect_out, actual_out,
+            filename or '', "Generated output")
     if diff:
         raise AssertionError("Conversion outputs did not match.\n%s" % diff)
 

virtManager/object/libvirtobject.py

@@ -5,6 +5,7 @@
 # See the COPYING file in the top-level directory.
 
 from virtinst import log
+from virtinst import xmlutil
 
 from ..baseclass import vmmGObject
 
@@ -43,11 +44,7 @@ class vmmLibvirtObject(vmmGObject):
                           obj)
             return
 
-        import difflib
-        diff = "".join(difflib.unified_diff(origxml.splitlines(1),
-                                            newxml.splitlines(1),
-                                            fromfile="Original XML",
-                                            tofile="New XML"))
+        diff = xmlutil.diff(origxml, newxml, "Original XML", "New XML")
         log.debug("Redefining %s with XML diff:\n%s", obj, diff)
 
     @staticmethod

virtinst/uri.py

@@ -9,11 +9,10 @@ import re
 import urllib.parse
 
 from .logger import log
+from . import xmlutil
 
 
 def sanitize_xml_for_test_define(xml):
-    import difflib
-
     orig = xml
     xml = re.sub("arch=\".*\"", "arch=\"i686\"", xml)
     xml = re.sub("domain type=\".*\"", "domain type=\"test\"", xml)
@@ -21,8 +20,7 @@ def sanitize_xml_for_test_define(xml):
     xml = re.sub(">exe<", ">hvm<", xml)
     xml = re.sub(">linux<", ">xen<", xml)
 
-    diff = "\n".join(difflib.unified_diff(orig.split("\n"),
-                                          xml.split("\n")))
+    diff = xmlutil.diff(orig, xml)
     if diff:
         log.debug("virtinst test sanitizing diff\n:%s", diff)
     return xml

virtinst/virtxml.py

@@ -5,7 +5,6 @@
 # This work is licensed under the GNU GPLv2 or later.
 # See the COPYING file in the top-level directory.
 
-import difflib
 import sys
 
 import libvirt
@@ -37,16 +36,13 @@ def prompt_yes_or_no(msg):
 
 
 def get_diff(origxml, newxml):
-    ret = "".join(difflib.unified_diff(origxml.splitlines(1),
-                                       newxml.splitlines(1),
-                                       fromfile="Original XML",
-                                       tofile="Altered XML"))
+    diff = xmlutil.diff(origxml, newxml, "Original XML", "Altered XML")
 
-    if ret:
-        log.debug("XML diff:\n%s", ret)
+    if diff:
+        log.debug("XML diff:\n%s", diff)
     else:
         log.debug("No XML diff, didn't generate any change.")
-    return ret
+    return diff
 
 
 def set_os_variant(options, guest):

virtinst/xmlutil.py

@@ -68,3 +68,11 @@ def set_prop_path(obj, prop_path, value):
 
 def in_testsuite():
     return "VIRTINST_TEST_SUITE" in os.environ
+
+
+def diff(origstr, newstr, fromfile="Original", tofile="New"):
+    import difflib
+    dlist = difflib.unified_diff(
+            origstr.splitlines(1), newstr.splitlines(1),
+            fromfile=fromfile, tofile=tofile)
+    return "".join(dlist)