t/{t5541,lib-httpd}: replace problematic '!()' notation with test_must_fail

diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index 19c72f55bf60c746f72e640e24043b2d83e00fe3..196827e7eacf0584379630f528fb7a4400f2b865 100755 (executable)
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -11,7 +11,7 @@ Testing basic diff tool invocation
 . ./test-lib.sh
 
 if ! test_have_prereq PERL; then
-       say 'skipping difftool tests, perl not available'
+       skip_all='skipping difftool tests, perl not available'
        test_done
 fi
 
@@ -92,6 +92,15 @@ test_expect_success 'difftool honors --gui' '
        restore_test_defaults
 '
 
+test_expect_success 'difftool --gui works without configured diff.guitool' '
+       git config diff.tool test-tool &&
+
+       diff=$(git difftool --no-prompt --gui branch) &&
+       test "$diff" = "branch" &&
+
+       restore_test_defaults
+'
+
 # Specify the diff tool using $GIT_DIFF_TOOL
 test_expect_success 'GIT_DIFF_TOOL variable' '
        git config --unset diff.tool