Re: [PATCH] t1002: stop using sum(1)

> Hi,
> 
> René Scharfe wrote:
> 
>> sum(1) is a command for calculating checksums of the contents of files.
>> It was part of early editions of Unix ("Research Unix", 1972/1973, [1]).
>> cksum(1) appeared in 4.4BSD (1993) as a replacement [2], and became part
>> of POSIX.1-2008 [3].  OpenBSD 5.6 (2014) removed sum(1).
>>
>> We only use sum(1) in t1002 to check for changes in three files.  On
>> MinGW we use md5sum(1) instead.  We could switch to the standard command
>> cksum(1) for all platforms; MinGW comes with GNU coreutils now, which
>> provides sum(1), cksum(1) and md5sum(1).  Use our standard method for
>> checking for file changes instead: test_cmp.
>>
>> It's more convenient because it shows differences nicely, it's faster on
>> MinGW because we have a special implementation there based only on
>> shell-internal commands, it's simpler as it allows us to avoid stripping
>> out unnecessary entries from the checksum file using grep(1), and it's
>> more consistent with the rest of the test suite.
>>
>> We already compare changed files with their expected new contents using
>> diff(1), so we don't need to check with "test_must_fail test_cmp" if
>> they differ from their original state.  A later patch could convert the
>> direct diff(1) calls to test_cmp as well.
>>
>> With all sum(1) calls gone, remove the MinGW-specific implementation
>> from test-lib.sh as well.
>>
>> [1] http://minnie.tuhs.org/cgi-bin/utree.pl?file=V3/man/man1/sum.1
>> [2] http://minnie.tuhs.org/cgi-bin/utree.pl?file=4.4BSD/usr/share/man/cat1/cksum.0
>> [3] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/cksum.html
>> ---
>>   t/t1002-read-tree-m-u-2way.sh | 67 ++++++++++++++++++++++---------------------
>>   t/test-lib.sh                 |  3 --
>>   2 files changed, 35 insertions(+), 35 deletions(-)
> 
> Nicely analyzed.  May we forge your sign-off?
> 
> [...]
>> --- a/t/t1002-read-tree-m-u-2way.sh
>> +++ b/t/t1002-read-tree-m-u-2way.sh
> [...]
>> @@ -132,8 +138,8 @@ test_expect_success \
>>        git ls-files --stage >7.out &&
>>        test_cmp M.out 7.out &&
>>        check_cache_at frotz dirty &&
>> -     sum bozbar frotz nitfol >actual7.sum &&
>> -     if cmp M.sum actual7.sum; then false; else :; fi &&
>> +     test_cmp bozbar.M bozbar &&
>> +     test_cmp nitfol.M nitfol &&
> 
> This one is strange.  What is that '! cmp' trying to check for?
> Does the replacement capture the same thing?
> 
> E.g., does it need a '! test_cmp frotz.M frotz &&' line?