Subject: Re: [PATCH 2/3] t7800: fix tests when difftool uses --no-symlinks

From: John Keeping <[email-masked]>
Date: Fri, 22 Mar 2013 23:05:16 +0000

On Fri, Mar 22, 2013 at 03:53:38PM -0700, Junio C Hamano wrote:
> John Keeping <[email-masked]> writes:
> 
> > When 'git difftool --dir-diff' is using --no-symlinks (either explicitly
> > or implicitly because it's running on Windows), any working tree files
> > that have been copied to the temporary directory are copied back after
> > the difftool completes.  This includes untracked files in the working
> > tree.
> 
> Hmph.  Why do we populate the temporary directory with a copy of an
> untracked path in the first place?  I thought the point of dir-diff
> was to materialize only the relevant paths to two temporaries and
> compare these temporaries with a tool that knows how to compare two
> directories?
> 
> Even if you had path F in HEAD that you are no longer tracking in
> the working tree, a normal
> 
> 	$ git diff HEAD
> 
> would report the path F to have been deleted, so I would imagine
> that the preimage side of the temporary directory should get a copy
> of HEAD:F at path F, while the postimage side of the temporary
> directory should not even have anything at path F, when dir-diff
> runs, no?
> 
> Isn't that the real reason why the test fails?  The path 'output' is
> not being tracked at any revision or in the index that is involved
> in the test, is it?

Actually it is, which is what I missed earlier.

A couple of tests before this 'setup change in subdirectory' does 'git
add .' which is far more general than it needs.  Perhaps this is a
better change:

diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index bba8a9d..561c993 100755
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -314,7 +314,7 @@ test_expect_success PERL 'setup change in subdirectory' '
 	git commit -m "added sub/sub" &&
 	echo test >>file &&
 	echo test >>sub/sub &&
-	git add . &&
+	git add file sub/sub &&
 	git commit -m "modified both"
 '

> > During the tests, this means that the following sequence occurs:
> >
> > 1) the shell opens "output" to redirect the difftool output
> > 2) difftool copies the empty "output" to the temporary directory
> > 3) difftool runs "ls" which writes to "output"
> > 4) difftool copies the empty "output" file back over the output of the
> >    command
> > 5) the output files doesn't contain the expected output, causing the
> >    test to fail
> >
> > Avoid this by writing the output into .git/ which will not be copied or
> > overwritten.
> 
> It is a good idea to move these test output and expect test vectore
> files to a different place to make it easier to distinguish them
> from test input (e.g. "sub", "file", etc.) in general, but the
> description of the original problem sounds like it is just working
> around a bug to me.  What am I missing?

I think there is a bug, as described in the paragraph below, and this
test should be made independent of that.  In light of the above I think
we can drop this patch and do this with that change instead.

> > In the longer term, difftool probably needs to learn to warn the user
> > instead of overwrite any changes that have been made to the working tree
> > file.
> >
> > Signed-off-by: John Keeping <[email-masked]>
> > ---
> >  t/t7800-difftool.sh | 24 ++++++++++++------------
> >  1 file changed, 12 insertions(+), 12 deletions(-)
> >
> > diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
> > index e694972..1eed439 100755
> > --- a/t/t7800-difftool.sh
> > +++ b/t/t7800-difftool.sh
> > @@ -319,29 +319,29 @@ test_expect_success PERL 'setup change in subdirectory' '
> >  '
> >  
> >  test_expect_success PERL 'difftool -d' '
> > -	git difftool -d --extcmd ls branch >output &&
> > -	grep sub output &&
> > -	grep file output
> > +	git difftool -d --extcmd ls branch >.git/output &&
> > +	grep sub .git/output &&
> > +	grep file .git/output
> >  '
> >  
> >  test_expect_success PERL 'difftool --dir-diff' '
> > -	git difftool --dir-diff --extcmd ls branch >output &&
> > -	grep sub output &&
> > -	grep file output
> > +	git difftool --dir-diff --extcmd ls branch >.git/output &&
> > +	grep sub .git/output &&
> > +	grep file .git/output
> >  '
> >  
> >  test_expect_success PERL 'difftool --dir-diff ignores --prompt' '
> > -	git difftool --dir-diff --prompt --extcmd ls branch >output &&
> > -	grep sub output &&
> > -	grep file output
> > +	git difftool --dir-diff --prompt --extcmd ls branch >.git/output &&
> > +	grep sub .git/output &&
> > +	grep file .git/output
> >  '
> >  
> >  test_expect_success PERL 'difftool --dir-diff from subdirectory' '
> >  	(
> >  		cd sub &&
> > -		git difftool --dir-diff --extcmd ls branch >output &&
> > -		grep sub output &&
> > -		grep file output
> > +		git difftool --dir-diff --extcmd ls branch >../.git/output &&
> > +		grep sub ../.git/output &&
> > +		grep file ../.git/output
> >  	)
> >  '
> --
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