Add test

tests/functional/tarball.sh

@@ -73,13 +73,13 @@ test_tarball .gz gzip
 # All entries in tree.tar.gz refer to the same file, and all have the same inode when unpacked by GNU tar.
 # We don't preserve the hard links, because that's an optimization we think is not worth the complexity,
 # so we only make sure that the contents are copied correctly.
-path="$(nix flake prefetch --json "tarball+file://$(pwd)/tree.tar.gz" | jq -r .storePath)"
-[[ $(cat "$path/a/b/foo") = bar ]]
-[[ $(cat "$path/a/b/xyzzy") = bar ]]
-[[ $(cat "$path/a/yyy") = bar ]]
-[[ $(cat "$path/a/zzz") = bar ]]
-[[ $(cat "$path/c/aap") = bar ]]
-[[ $(cat "$path/fnord") = bar ]]
+nix flake prefetch --json "tarball+file://$(pwd)/tree.tar.gz" --out-link "$TEST_ROOT/result"
+[[ $(cat "$TEST_ROOT/result/a/b/foo") = bar ]]
+[[ $(cat "$TEST_ROOT/result/a/b/xyzzy") = bar ]]
+[[ $(cat "$TEST_ROOT/result/a/yyy") = bar ]]
+[[ $(cat "$TEST_ROOT/result/a/zzz") = bar ]]
+[[ $(cat "$TEST_ROOT/result/c/aap") = bar ]]
+[[ $(cat "$TEST_ROOT/result/fnord") = bar ]]
 
 # Test a tarball that has multiple top-level directories.
 rm -rf "$TEST_ROOT/tar_root"