From: Elijah Newren <redacted>

It turns out the t7063 has some testcases that even without using the
untracked cache cover situations that nothing else in the testsuite
handles.  Checking the results of
  git status --porcelain
both with and without the untracked cache, and comparing both against
our expected results helped uncover a critical bug in some dir.c
restructuring.

Unfortunately, it's not easy to run status and tell it to ignore the
untracked cache; the only knob we have it to instruct it to *delete*
(and ignore) the untracked cache.

Create a simple helper that will create a clone of the index that is
missing the untracked cache bits, and use it to compare that the results
with the untracked cache match the results we get without the untracked
cache.

Signed-off-by: Elijah Newren <redacted>
---
 t/t7063-status-untracked-cache.sh | 52 +++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/t/t7063-status-untracked-cache.sh b/t/t7063-status-untracked-cache.sh
index 190ae149cf3..156d06c34e8 100755
--- a/t/t7063-status-untracked-cache.sh
+++ b/t/t7063-status-untracked-cache.sh

@@ -30,6 +30,30 @@ status_is_clean() {
 	test_must_be_empty ../status.actual
 }
 
+# Ignore_Untracked_Cache, abbreviated to 3 letters because then people can
+# compare commands side-by-side, e.g.
+#    iuc status --porcelain >expect &&
+#    git status --porcelain >actual &&
+#    test_cmp expect actual
+iuc() {
+	git ls-files -s >../current-index-entries
+	git ls-files -t | grep ^S | sed -e s/^S.// >../current-sparse-entries
+
+	GIT_INDEX_FILE=.git/tmp_index
+	export GIT_INDEX_FILE
+	git update-index --index-info <../current-index-entries
+	git update-index --skip-worktree $(cat ../current-sparse-entries)
+
+	git -c core.untrackedCache=false "$@"
+	ret=$?
+
+	rm ../current-index-entries
+	rm $GIT_INDEX_FILE
+	unset GIT_INDEX_FILE
+
+	return $ret
+}