t/test-lib: add an SHA1 prerequisite

diff --git a/t/t6120-describe.sh b/t/t6120-describe.sh
index a5d901502414f25616a474152ee0f5816465bd37..bae78c4e89e2402d5ab37e3b7cd094dde41d69b3 100755 (executable)
--- a/t/t6120-describe.sh
+++ b/t/t6120-describe.sh
@@ -378,4 +378,12 @@ check_describe tags/A --all A
 check_describe tags/c --all c
 check_describe heads/branch_A --all --match='branch_*' branch_A
 
+test_expect_success 'describe complains about tree object' '
+       test_must_fail git describe HEAD^{tree}
+'
+
+test_expect_success 'describe complains about missing object' '
+       test_must_fail git describe $_z40
+'
+
 test_done