test: test_must_be_empty helper

diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index 1de0ebda25c1034fc1b343a8f0e3da9c2c7f8c6e..c1d2cbad2d3ee0ac77df9e4ff8115d1db9a7ac5c 100755 (executable)
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -179,7 +179,7 @@ test_expect_success 'default to @{upstream} when upstream arg is missing' '
 test_expect_success 'rebase -q is quiet' '
        git checkout -b quiet topic &&
        git rebase -q master >output.out 2>&1 &&
-       test ! -s output.out
+       test_must_be_empty output.out
 '
 
 test_expect_success 'Rebase a commit that sprinkles CRs in' '