[PATCH 7/9] update-index: add tests for sparse-checkout compatibility

["Victoria Dye via GitGitGadget" <gitgitgadget@gmail.com>]

From: Victoria Dye <vdye@github.com>

Introduce tests for a variety of `git update-index` use cases, including
performance scenarios. Tests for `update-index add/remove` are specifically
focused on how `git stash` uses `git update-index` as a subcommand to
prepare for sparse index integration with `stash` in a future series.

Co-authored-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Victoria Dye <vdye@github.com>
---
 t/perf/p2000-sparse-operations.sh        |   1 +
 t/t1092-sparse-checkout-compatibility.sh | 125 +++++++++++++++++++++++
 2 files changed, 126 insertions(+)

diff --git a/t/perf/p2000-sparse-operations.sh b/t/perf/p2000-sparse-operations.sh
index 54f8602f3c1..7dbed330160 100755
--- a/t/perf/p2000-sparse-operations.sh
+++ b/t/perf/p2000-sparse-operations.sh
@@ -118,5 +118,6 @@ test_perf_on_all git diff --cached
 test_perf_on_all git blame $SPARSE_CONE/a
 test_perf_on_all git blame $SPARSE_CONE/f3/a
 test_perf_on_all git checkout-index -f --all
+test_perf_on_all git update-index --add --remove
 
 test_done
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index 6ecf1f2bf8e..6804ab23a27 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -630,6 +630,131 @@ test_expect_success 'reset with wildcard pathspec' '
 	test_all_match git ls-files -s -- folder1
 '
 
+test_expect_success 'update-index modify outside sparse definition' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+
+	# Create & modify folder1/a
+	run_on_sparse mkdir -p folder1 &&
+	run_on_sparse cp ../initial-repo/folder1/a folder1/a &&
+	run_on_all ../edit-contents folder1/a &&
+
+	# If file has skip-worktree enabled, update-index does not modify the
+	# index entry
+	test_sparse_match git update-index folder1/a &&
+	test_sparse_match git status --porcelain=v2 &&
+	test_must_be_empty sparse-checkout-out &&
+
+	# When skip-worktree is disabled (even on files outside sparse cone), file
+	# is updated in the index
+	test_sparse_match git update-index --no-skip-worktree folder1/a &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git update-index folder1/a &&
+	test_all_match git status --porcelain=v2
+'
+
+test_expect_success 'update-index --add outside sparse definition' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+
+	# Create folder1, add new file
+	run_on_sparse mkdir -p folder1 &&
+	run_on_all ../edit-contents folder1/b &&
+
+	# Similar to `git add`, the untracked out-of-cone file is added to the index
+	# identically across sparse and non-sparse checkouts
+	test_all_match git update-index --add folder1/b &&
+	test_all_match git status --porcelain=v2
+'
+
+test_expect_success 'update-index --remove outside sparse definition' '
+	init_repos &&
+
+	# When `--ignore-skip-worktree-entries` is specified, out-of-cone files are
+	# not removed from the index if they do not exist on disk
+	test_sparse_match git update-index --remove --ignore-skip-worktree-entries folder1/a &&
+	test_all_match git status --porcelain=v2 &&
+
+	# When the flag is _not_ specified, out-of-cone, not-on-disk files are
+	# removed from the index
+	rm full-checkout/folder1/a &&
+	test_all_match git update-index --remove folder1/a &&
+	test_all_match git status --porcelain=v2 &&
+
+	# NOTE: --force-remove supercedes --ignore-skip-worktree-entries, removing
+	# a skip-worktree file from the index (and disk) when both are specified
+	test_all_match git update-index --force-remove --ignore-skip-worktree-entries folder1/a &&
+	test_all_match git status --porcelain=v2
+'
+
+test_expect_success 'update-index with directories' '
+	init_repos &&
+
+	# update-index will exit silently when provided with a directory name
+	# containing a trailing slash
+	test_all_match git update-index deep/ folder1/ &&
+	grep "Ignoring path deep/" sparse-checkout-err &&
+	grep "Ignoring path folder1/" sparse-checkout-err &&
+
+	# When update-index is given a directory name WITHOUT a trailing slash, it will
+	# behave in different ways depending on the status of the directory on disk:
+	# * if it exists, the command exits with an error ("add individual files instead")
+	# * if it does NOT exist (e.g., in a sparse-checkout), it is assumed to be a
+	#   file and either triggers an error ("does not exist  and --remove not passed")
+	#   or is ignored completely (when using --remove)
+	test_all_match test_must_fail git update-index deep &&
+	run_on_all test_must_fail git update-indexe folder1 &&
+	test_must_fail git -C full-checkout update-index --remove folder1 &&
+	test_sparse_match git update-index --remove folder1 &&
+	test_all_match git status --porcelain=v2
+'
+
+test_expect_success 'update-index --again file outside sparse definition' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+
+	test_all_match git checkout -b test-reupdate &&
+
+	# Update HEAD without modifying the index to introduce a difference in
+	# folder1/a
+	test_sparse_match git reset --soft update-folder1 &&
+
+	# Because folder1/a differs in the index vs HEAD,
+	# `git update-index --remove --again` will effectively perform
+	# `git update-index --remove folder1/a` and remove the folder1/a
+	test_sparse_match git update-index --remove --again &&
+	test_sparse_match git status --porcelain=v2
+'
+
+test_expect_success 'update-index --cacheinfo' '
+	init_repos &&
+
+	deep_a_oid=$(git -C full-checkout rev-parse update-deep:deep/a) &&
+	folder2_oid=$(git -C full-checkout rev-parse update-folder2:folder2) &&
+	folder1_a_oid=$(git -C full-checkout rev-parse update-folder1:folder1/a) &&
+
+	test_all_match git update-index --cacheinfo 100644 $deep_a_oid deep/a &&
+	test_all_match git status --porcelain=v2 &&
+
+	# Cannot add sparse directory, even in sparse index case
+	test_all_match test_must_fail git update-index --add --cacheinfo 040000 $folder2_oid folder2/ &&
+
+	# Sparse match only - because folder1/a is outside the sparse checkout
+	# definition (and thus not on-disk), it will appear "deleted" in
+	# unstaged changes.
+	test_all_match git update-index --add --cacheinfo 100644 $folder1_a_oid folder1/a &&
+	test_sparse_match git status --porcelain=v2
+'
+
 test_expect_success 'merge, cherry-pick, and rebase' '
 	init_repos &&
 
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