test-lib: Make the test_external_* functions TAP-aware

diff --git a/t/t7401-submodule-summary.sh b/t/t7401-submodule-summary.sh
index d3c039f724c3a1247417b5fd29d6bd50a88f54be..cee319da0ae6ef9ec3b220adbb178e116713db2a 100755 (executable)
--- a/t/t7401-submodule-summary.sh
+++ b/t/t7401-submodule-summary.sh
@@ -227,4 +227,11 @@ test_expect_success 'fail when using --files together with --cached' "
     test_must_fail git submodule summary --files --cached
 "
 
+test_expect_success 'should not fail in an empty repo' "
+    git init xyzzy &&
+    cd xyzzy &&
+    git submodule summary >output 2>&1 &&
+    test_cmp output /dev/null
+"
+
 test_done