iso-wrapper: Remove hacks for sorting

We can use a key function instead of relying to the deprecated cmp. This
makes the code work on Python 2.6 and on recent versions it makes it
faster.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

pungi/wrappers/iso.py

@@ -15,22 +15,14 @@
 
 
 import os
-import sys
 from fnmatch import fnmatch
 import contextlib
-from functools import cmp_to_key
 from six.moves import shlex_quote
 
 from kobo.shortcuts import force_list, relative_path, run
 from pungi import util
 
 
-# HACK: define cmp in python3
-if sys.version_info[0] == 3:
-    def cmp(a, b):
-        return (a > b) - (a < b)
-
-
 def get_boot_options(arch, createfrom, efi=True):
     """Checks to see what we need as the -b option for mkisofs"""
 
@@ -342,7 +334,7 @@ def write_graft_points(file_name, h, exclude=None):
         seen_dirs.add(dn)
 
     f = open(file_name, "w")
-    for i in sorted(result, key=cmp_to_key(cmp_graft_points)):
+    for i in sorted(result, key=graft_point_sort_key):
         # make sure all files required for boot come first,
         # otherwise there may be problems with booting (large LBA address, etc.)
         found = False
@@ -357,9 +349,7 @@ def write_graft_points(file_name, h, exclude=None):
 
 
 def _is_rpm(path):
-    if path.endswith(".rpm"):
-        return True
-    return False
+    return path.endswith(".rpm")
 
 
 def _is_image(path):
@@ -380,27 +370,12 @@ def _is_image(path):
     return False
 
 
-def cmp_graft_points(x, y):
-    x_is_rpm = _is_rpm(x)
-    y_is_rpm = _is_rpm(y)
-    x_is_image = _is_image(x)
-    y_is_image = _is_image(y)
-
-    if x_is_rpm and y_is_rpm:
-        return cmp(x, y)
-    if x_is_rpm:
-        return 1
-    if y_is_rpm:
-        return -1
-
-    if x_is_image and y_is_image:
-        return cmp(x, y)
-    if x_is_image:
-        return -1
-    if y_is_image:
-        return 1
-
-    return cmp(x, y)
+def graft_point_sort_key(x):
+    """
+    Images are sorted first, followed by other files. RPMs always come last.
+    In the same group paths are sorted alphabetically.
+    """
+    return (0 if _is_image(x) else 2 if _is_rpm(x) else 1, x)
 
 
 @contextlib.contextmanager

tests/test_iso_wrapper.py

@@ -4,6 +4,7 @@ import mock
 import os
 import sys
 import unittest
+import itertools
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
 
@@ -75,3 +76,35 @@ class TestIsoUtils(unittest.TestCase):
         self.assertEqual(len(mock_run.call_args_list), 1)
         self.assertEqual(len(mock_unmount.call_args_list), 0)
         self.assertEqual(len(log.mock_calls), 1)
+
+
+class TestCmpGraftPoints(unittest.TestCase):
+    def assertSorted(self, *args):
+        """Tests that all permutations of arguments yield the same sorted results."""
+        for perm in itertools.permutations(args):
+            self.assertEqual(sorted(perm, key=iso.graft_point_sort_key),
+                             list(args))
+
+    def test_eq(self):
+        self.assertSorted('pkgs/foo.rpm', 'pkgs/foo.rpm')
+
+    def test_rpms_sorted_alphabetically(self):
+        self.assertSorted('pkgs/bar.rpm', 'pkgs/foo.rpm')
+
+    def test_images_sorted_alphabetically(self):
+        self.assertSorted('aaa.img', 'images/foo', 'isolinux/foo')
+
+    def test_other_files_sorted_alphabetically(self):
+        self.assertSorted('bar.txt', 'foo.txt')
+
+    def test_rpms_after_images(self):
+        self.assertSorted('foo.ins', 'bar.rpm')
+
+    def test_other_after_images(self):
+        self.assertSorted('EFI/anything', 'zzz.txt')
+
+    def test_rpm_after_other(self):
+        self.assertSorted('bbb.txt', 'aaa.rpm')
+
+    def test_all_kinds(self):
+        self.assertSorted('etc/file', 'ppc/file', 'c.txt', 'd.txt', 'a.rpm', 'b.rpm')