[Zope3-dev] test_merge_diff3 unit test failure

[Dave Harris]

I included this failure in my Windows XP unit test report a couple of days 
ago and I've identified the source of the failure. Here's the traceback:

======================================================================
FAIL: test_merge_diff3 (zope.fssync.tests.test_fsmerger.TestFSMerger)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "D:\sf\Zope3\src\zope\fssync\tests\test_fsmerger.py", line 267, in 
test_merge_diff3
    self.entry, self.entry)
  File "D:\sf\Zope3\src\zope\fssync\tests\test_fsmerger.py", line 234, in 
mergetest
    self.assertEqual(filtered_reports, expected_reports)
  File "C:\PYTHON23\Lib\unittest.py", line 302, in failUnlessEqual
    raise self.failureException, \
AssertionError: ['C 
c:\\docume~1\\owner\\locals~1\\temp\\tmpxih9yg\\local\\foo'] != ['M 
c:\\docume~1\\owner\\locals~1\\temp\\tmpxih9yg\\local\\foo']

----------------------------------------------------------------------

The root of the problem is the diff3 / popen() combination in the function 
merge_files_merge() in fssync/merger.py:

    def merge_files_merge(self, local, original, remote):
        # XXX This is platform dependent
        if exists(original):
            origfile = original
        else:
            origfile = "/dev/null"
        # commands.mkarg() is undocumented; maybe use fssync.quote()
        cmd = "diff3 -m -E %s %s %s" % (commands.mkarg(local),
                                        commands.mkarg(origfile),
                                        commands.mkarg(remote))
        pipe = os.popen(cmd, "r")
        output = pipe.read()
        sts = pipe.close()
        ......

The mkarg() calls place quotes around each of the file names, which the 
Windows diff3 command finds distasteful. Using pdb, I traced down to the 
popen() and:

>>>print cmd
diff3 -m -E 'local\foo' 'original\foo' 'remote\foo'

>From the Windows console, this works:

diff3 -m -E fish.txt slapping.txt dance.txt

but this does not:

diff3 -m -E 'fish.txt' 'slapping.txt' 'dance.txt'
diff3: 'fish.txt': No such file or directory.

Here's the version of diff3 that I'm using (diff3 -v):
diff3 (GNU diffutils) 2.7.2 [This is the version distributed in 'Programming 
Python']

Version 2.8.1 of diff3 doesn't seem to work at all (except to display a 
version number.)

I did find a version which was included in the Msys 1.0 distribution, which 
has a slightly different version identification:
diff3 GNU diffutils 2.7 [notice the lack of parentheses]

This version will accept single quotes around the file name arguments. AND 
this version will permit the test_merge_diff3 test to run to completion.

One note: The diffe and the file msys-1.0.dll must be somewhere in the 
Windows PATH.

With this change, I can now run all unit tests without a failure on Windows 
XP.

Dave Harris