tests: use 'test_must_be_empty' instead of '! test -s'

Using 'test_must_be_empty' is preferable to '! test -s', because it
gives a helpful error message if the given file is unexpectedly not
empty, while the latter remains completely silent.  Furthermore, it
also catches cases when the given file unexpectedly does not exist at
all.

This patch was basically created by:

  sed -i -e 's/! test -s/test_must_be_empty/' t[0-9]*.sh

with the following notable exceptions:

  - The '! test -s' check in '.gitmodules ignore=dirty suppresses
    submodules with untracked content' in 't7508-status.sh' is left
    as-is, because it's bogus and, therefore, it's subject of a
    dedicated patch.

  - The '! test -s' checks in 't9131-git-svn-empty-symlink.sh' and
    't9135-git-svn-moved-branch-empty-file.sh' are immediately
    preceeded by a 'test -f' to ensure that the files exist in the
    first place.  'test_must_be_empty' ensures that as well, so those
    'test -f' commands are removed as well.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index fc44ec9..825da14 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -941,7 +941,7 @@ test_expect_success 'grep from a subdirectory to search wider area (2)' '
 	(
 		cd s || exit 1
 		( git grep xxyyzz .. >out ; echo $? >status )
-		! test -s out &&
+		test_must_be_empty out &&
 		test 1 = $(cat status)
 	)
 '