osx: new script for generating OS X package versions

If you're shipping prerelease or rc packages using Munki, you'll
eventually discover that Munki's version comparison logic is not as
good as pip's. In theory we should be able to fix Munki, but it seems
entirely reasonable to produce version strings that sort reasonably
under these conditions. Since the requried logic not brief, add a new
script and some tests of that logic.

A followup change will wire this into the Makefile.

contrib/genosxversion.py

@@ -0,0 +1,130 b''
+#!/usr/bin/env python2
+from __future__ import absolute_import, print_function
+
+import argparse
+import json
+import os
+import subprocess
+import sys
+
+# Always load hg libraries from the hg we can find on $PATH.
+hglib = json.loads(subprocess.check_output(
+    ['hg', 'debuginstall', '-Tjson']))[0]['hgmodules']
+sys.path.insert(0, os.path.dirname(hglib))
+
+from mercurial import util
+
+ap = argparse.ArgumentParser()
+ap.add_argument('--paranoid',
+                action='store_true',
+                help=("Be paranoid about how version numbers compare and "
+                      "produce something that's more likely to sort "
+                      "reasonably."))
+ap.add_argument('--selftest', action='store_true', help='Run self-tests.')
+ap.add_argument('versionfile', help='Path to a valid mercurial __version__.py')
+
+def paranoidver(ver):
+    """Given an hg version produce something that distutils can sort.
+
+    Some Mac package management systems use distutils code in order to
+    figure out upgrades, which makes life difficult. The test case is
+    a reduced version of code in the Munki tool used by some large
+    organizations to centrally manage OS X packages, which is what
+    inspired this kludge.
+
+    >>> paranoidver('3.4')
+    '3.4.0'
+    >>> paranoidver('3.4.2')
+    '3.4.2'
+    >>> paranoidver('3.0-rc+10')
+    '2.9.9999-rc+10'
+    >>> paranoidver('4.2+483-5d44d7d4076e')
+    '4.2.0+483-5d44d7d4076e'
+    >>> paranoidver('4.2.1+598-48d1e1214d8c')
+    '4.2.1+598-48d1e1214d8c'
+    >>> paranoidver('4.3-rc')
+    '4.2.9999-rc'
+    >>> paranoidver('4.3')
+    '4.3.0'
+    >>> from distutils import version
+    >>> class LossyPaddedVersion(version.LooseVersion):
+    ...     '''Subclass version.LooseVersion to compare things like
+    ...     "10.6" and "10.6.0" as equal'''
+    ...     def __init__(self, s):
+    ...             self.parse(s)
+    ...
+    ...     def _pad(self, version_list, max_length):
+    ...         'Pad a version list by adding extra 0 components to the end'
+    ...         # copy the version_list so we don't modify it
+    ...         cmp_list = list(version_list)
+    ...         while len(cmp_list) < max_length:
+    ...             cmp_list.append(0)
+    ...         return cmp_list
+    ...
+    ...     def __cmp__(self, other):
+    ...         if isinstance(other, str):
+    ...             other = MunkiLooseVersion(other)
+    ...         max_length = max(len(self.version), len(other.version))
+    ...         self_cmp_version = self._pad(self.version, max_length)
+    ...         other_cmp_version = self._pad(other.version, max_length)
+    ...         return cmp(self_cmp_version, other_cmp_version)
+    >>> def testver(older, newer):
+    ...   o = LossyPaddedVersion(paranoidver(older))
+    ...   n = LossyPaddedVersion(paranoidver(newer))
+    ...   return o < n
+    >>> testver('3.4', '3.5')
+    True
+    >>> testver('3.4.0', '3.5-rc')
+    True
+    >>> testver('3.4-rc', '3.5')
+    True
+    >>> testver('3.4-rc+10-deadbeef', '3.5')
+    True
+    >>> testver('3.4.2', '3.5-rc')
+    True
+    >>> testver('3.4.2', '3.5-rc+10-deadbeef')
+    True
+    >>> testver('4.2+483-5d44d7d4076e', '4.2.1+598-48d1e1214d8c')
+    True
+    >>> testver('4.3-rc', '4.3')
+    True
+    >>> testver('4.3', '4.3-rc')
+    False
+    """
+    major, minor, micro, extra = util.versiontuple(ver, n=4)
+    if micro is None:
+        micro = 0
+    if extra:
+        if extra.startswith('rc'):
+            if minor == 0:
+                major -= 1
+                minor = 9
+            else:
+                minor -= 1
+            micro = 9999
+            extra = '-' + extra
+        else:
+            extra = '+' + extra
+    else:
+        extra = ''
+    return '%d.%d.%d%s' % (major, minor, micro, extra)
+
+def main(argv):
+    opts = ap.parse_args(argv[1:])
+    if opts.selftest:
+        import doctest
+        doctest.testmod()
+        return
+    with open(opts.versionfile) as f:
+        for l in f:
+            if l.startswith('version = '):
+                # version number is entire line minus the quotes
+                ver = l[len('version = ') + 1:-2]
+                break
+    if opts.paranoid:
+        print(paranoidver(ver))
+    else:
+        print(ver)
+
+if __name__ == '__main__':
+    main(sys.argv)

tests/test-mac-packages.t

@@ -9,6 +9,7 b''
   $ export KEEPMPKG
 
   $ cd "$TESTDIR"/..
+  $ contrib/genosxversion.py --selftest ignoredarg
   $ make osx > "$OUTPUTDIR/build.log" 2>&1
   $ cd "$OUTPUTDIR"
   $ ls -d *.pkg