test-lib: allow negation of prerequisites

diff --git a/t/t7501-commit.sh b/t/t7501-commit.sh
index 0f83be80efa0fa8d25dd667b2a667c8406df787f..195e7477d883f39d51f5740b5b309a489dd92d3d 100755 (executable)
--- a/t/t7501-commit.sh
+++ b/t/t7501-commit.sh
@@ -108,6 +108,16 @@ test_expect_success 'amend commit' '
        EDITOR=./editor git commit --amend
 '
 
+test_expect_success 'amend --only ignores staged contents' '
+       cp file file.expect &&
+       echo changed >file &&
+       git add file &&
+       git commit --no-edit --amend --only &&
+       git cat-file blob HEAD:file >file.actual &&
+       test_cmp file.expect file.actual &&
+       git diff --exit-code
+'
+
 test_expect_success 'set up editor' '
        cat >editor <<-\EOF &&
        #!/bin/sh