tests: use 'test_must_be_empty' instead of 'test_cmp <empty> <out>'

Using 'test_must_be_empty' is shorter and more idiomatic than

  >empty &&
  test_cmp empty out

as it saves the creation of an empty file.  Furthermore, sometimes the
expected empty file doesn't have such a descriptive name like 'empty',
and its creation is far away from the place where it's finally used
for comparison (e.g. in 't7600-merge.sh', where two expected empty
files are created in the 'setup' test, but are used only about 500
lines later).

These cases were found by instrumenting 'test_cmp' to error out the
test script when it's used to compare empty files, and then converted
manually.

Note that even after this patch there still remain a lot of cases
where we use 'test_cmp' to check empty files:

  - Sometimes the expected output is not hard-coded in the test, but
    'test_cmp' is used to ensure that two similar git commands produce
    the same output, and that output happens to be empty, e.g. the
    test 'submodule update --merge  - ignores --merge  for new
    submodules' in 't7406-submodule-update.sh'.

  - Repetitive common tasks, including preparing the expected results
    and running 'test_cmp', are often extracted into a helper
    function, and some of this helper's callsites expect no output.

  - For the same reason as above, the whole 'test_expect_success'
    block is within a helper function, e.g. in 't3070-wildmatch.sh'.

  - Or 'test_cmp' is invoked in a loop, e.g. the test 'cvs update
    (-p)' in 't9400-git-cvsserver-server.sh'.

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

1 files changed, 5 insertions, 6 deletions

diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh
index 91fd71444d..a652f6002a 100755
--- a/t/t1450-fsck.sh
+++ b/t/t1450-fsck.sh
@@ -16,8 +16,7 @@ test_expect_success setup '
 	git checkout HEAD^0 &&
 	test_commit B fileB two &&
 	git tag -d A B &&
-	git reflog expire --expire=now --all &&
-	>empty
+	git reflog expire --expire=now --all
 '
 
 test_expect_success 'loose objects borrowed from alternate are not missing' '
@@ -29,12 +28,12 @@ test_expect_success 'loose objects borrowed from alternate are not missing' '
 		test_commit C fileC one &&
 		git fsck --no-dangling >../actual 2>&1
 	) &&
-	test_cmp empty actual
+	test_must_be_empty actual
 '
 
 test_expect_success 'HEAD is part of refs, valid objects appear valid' '
 	git fsck >actual 2>&1 &&
-	test_cmp empty actual
+	test_must_be_empty actual
 '
 
 # Corruption tests follow.  Make sure to remove all traces of the
@@ -346,12 +345,12 @@ test_expect_success 'tag with NUL in header' '
 
 test_expect_success 'cleaned up' '
 	git fsck >actual 2>&1 &&
-	test_cmp empty actual
+	test_must_be_empty actual
 '
 
 test_expect_success 'rev-list --verify-objects' '
 	git rev-list --verify-objects --all >/dev/null 2>out &&
-	test_cmp empty out
+	test_must_be_empty out
 '
 
 test_expect_success 'rev-list --verify-objects with bad sha1' '