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

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 22, 2013, 22:53 UTC
Message-ID: <7v8v5f59n1.fsf@alter.siamese.dyndns.org>
In-Reply-To: <5fc134f6c4a88232c78240539084e9d35db3a6cb.1363980749.git.john@keeping.me.uk>

John Keeping <john@keeping.me.uk> writes:

Show 5 quoted lines

> 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?

Show 12 quoted lines

> 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?

Show 54 quoted lines

> 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 <john@keeping.me.uk>
> ---
>  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
>  	)
>  '