test: use test_must_be_empty F instead of test -z $(cat F)

Use test_must_be_empty instead of reading the file and comparing its
contents to an empty string.  That's more efficient, as the function
only needs built-in meta-data only check in the usual case, and provides
nicer debug output otherwise.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/t/t1506-rev-parse-diagnosis.sh b/t/t1506-rev-parse-diagnosis.sh
index 624d0a588f..6d951ca015 100755
--- a/t/t1506-rev-parse-diagnosis.sh
+++ b/t/t1506-rev-parse-diagnosis.sh
@@ -138,10 +138,10 @@ test_expect_success 'incorrect file in :path and :N:path' '
 
 test_expect_success 'invalid @{n} reference' '
 	test_must_fail git rev-parse master@{99999} >output 2>error &&
-	test -z "$(cat output)" &&
+	test_must_be_empty output &&
 	grep "fatal: Log for [^ ]* only has [0-9][0-9]* entries." error  &&
 	test_must_fail git rev-parse --verify master@{99999} >output 2>error &&
-	test -z "$(cat output)" &&
+	test_must_be_empty output &&
 	grep "fatal: Log for [^ ]* only has [0-9][0-9]* entries." error
 '
 
@@ -155,13 +155,13 @@ test_expect_success 'relative path not found' '
 
 test_expect_success 'relative path outside worktree' '
 	test_must_fail git rev-parse HEAD:../file.txt >output 2>error &&
-	test -z "$(cat output)" &&
+	test_must_be_empty output &&
 	test_i18ngrep "outside repository" error
 '
 
 test_expect_success 'relative path when cwd is outside worktree' '
 	test_must_fail git --git-dir=.git --work-tree=subdir rev-parse HEAD:./file.txt >output 2>error &&
-	test -z "$(cat output)" &&
+	test_must_be_empty output &&
 	grep "relative path syntax can.t be used outside working tree." error
 '