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

diff --git a/t/t4041-diff-submodule-option.sh b/t/t4041-diff-submodule-option.sh
index 302f2166a9b84f5de05bbb7e6d7a2a791853e5fe..7a4594224b0d09ef946f52a7df4c310ad0e19866 100755 (executable)
--- a/t/t4041-diff-submodule-option.sh
+++ b/t/t4041-diff-submodule-option.sh
@@ -257,9 +257,7 @@ test_expect_success 'typechanged submodule(blob->submodule)' '
 commit_file sm1 &&
 test_expect_success 'submodule is up to date' '
        git diff-index -p --submodule=log HEAD >actual &&
-       cat >expected <<-EOF &&
-       EOF
-       test_cmp expected actual
+       test_must_be_empty actual
 '
 
 test_expect_success 'submodule contains untracked content' '