Elijah Newren wrote:

On Thu, Feb 24, 2022 at 2:34 PM Victoria Dye via GitGitGadget
[off-list ref] wrote:

quoted

From: Victoria Dye <redacted>

Add tests focused on how 'git read-tree' behaves in sparse checkouts. Extra
emphasis is placed on interactions with files outside the sparse cone, e.g.
merges with out-of-cone conflicts.

Signed-off-by: Victoria Dye <redacted>
---
 t/perf/p2000-sparse-operations.sh        |  1 +
 t/t1092-sparse-checkout-compatibility.sh | 85 ++++++++++++++++++++++++
 2 files changed, 86 insertions(+)

diff --git a/t/perf/p2000-sparse-operations.sh b/t/perf/p2000-sparse-operations.sh
index 2a7106b9495..382716cfca9 100755
--- a/t/perf/p2000-sparse-operations.sh
+++ b/t/perf/p2000-sparse-operations.sh

@@ -117,6 +117,7 @@ test_perf_on_all git diff
 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 read-tree -mu HEAD
 test_perf_on_all git checkout-index -f --all
 test_perf_on_all git update-index --add --remove $SPARSE_CONE/a

diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index b1dcaa0e642..9d58da4e925 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh

@@ -819,6 +819,91 @@ test_expect_success 'update-index --cacheinfo' '
        test_cmp expect sparse-checkout-out
 '

+test_expect_success 'read-tree --merge with files outside sparse definition' '
+       init_repos &&
+
+       test_all_match git checkout -b test-branch update-folder1 &&
+       for MERGE_TREES in "base HEAD update-folder2" \
+                          "update-folder1 update-folder2" \
+                          "update-folder2"
+       do
+               # Clean up and remove on-disk files
+               test_all_match git reset --hard HEAD &&
+               test_sparse_match git sparse-checkout reapply &&
+
+               # Although the index matches, without --no-sparse-checkout, outside-of-
+               # definition files will not exist on disk for sparse checkouts
+               test_all_match git read-tree -mu $MERGE_TREES &&
+               test_all_match git status --porcelain=v2 &&
+               test_path_is_missing sparse-checkout/folder2 &&
+               test_path_is_missing sparse-index/folder2 &&
+
+               test_all_match git read-tree --reset -u HEAD &&
+               test_all_match git status --porcelain=v2 &&
+
+               test_all_match git read-tree -mu --no-sparse-checkout $MERGE_TREES &&
+               test_all_match git status --porcelain=v2 &&
+               test_cmp sparse-checkout/folder2/a sparse-index/folder2/a &&
+               test_cmp sparse-checkout/folder2/a full-checkout/folder2/a || return 1
+       done
+'
+
+test_expect_success 'read-tree --merge with edit/edit conflicts in sparse directories' '
+       init_repos &&
+
+       # Merge of multiple changes to same directory (but not same files) should
+       # succeed
+       test_all_match git read-tree -mu base rename-base update-folder1 &&
+       test_all_match git status --porcelain=v2 &&
+
+       test_all_match git reset --hard &&
+
+       test_all_match git read-tree -mu rename-base update-folder2 &&
+       test_all_match git status --porcelain=v2 &&
+
+       test_all_match git reset --hard &&
+
+       test_all_match test_must_fail git read-tree -mu base update-folder1 rename-out-to-in &&
+       test_all_match test_must_fail git read-tree -mu rename-out-to-in update-folder1
+'
+
+test_expect_success 'read-tree --prefix outside sparse definition' '
+       init_repos &&
+
+       # Cannot read-tree --prefix with a single argument when files exist within
+       # prefix

Given the comments in the cover letter about --prefix needing special
work, it's not clear to me whether the below is expected behavior or
current-but-buggy behavior that you are testing and documenting.
Could you clarify?

It's expected - per 'Documentation/git-read-tree.txt':

	The command will refuse to overwrite entries that already
	existed in the original index file.

I'll update the comment to make that clearer. Thanks!

quoted

+       test_all_match test_must_fail git read-tree --prefix=folder1/ -u update-folder1 &&
+
+       test_all_match git read-tree --prefix=folder2/0 -u rename-base &&
+       test_path_is_missing sparse-checkout/folder2 &&
+       test_path_is_missing sparse-index/folder2 &&
+
+       test_all_match git read-tree --reset -u HEAD &&
+       test_all_match git read-tree --prefix=folder2/0 -u --no-sparse-checkout rename-base &&
+       test_cmp sparse-checkout/folder2/0/a sparse-index/folder2/0/a &&
+       test_cmp sparse-checkout/folder2/0/a full-checkout/folder2/0/a
+'
+
+test_expect_success 'read-tree --merge with directory-file conflicts' '
+       init_repos &&
+
+       test_all_match git checkout -b test-branch rename-base &&
+
+       # Although the index matches, without --no-sparse-checkout, outside-of-
+       # definition files will not exist on disk for sparse checkouts
+       test_sparse_match git read-tree -mu rename-out-to-out &&
+       test_sparse_match git status --porcelain=v2 &&
+       test_path_is_missing sparse-checkout/folder2 &&
+       test_path_is_missing sparse-index/folder2 &&
+
+       test_sparse_match git read-tree --reset -u HEAD &&
+       test_sparse_match git status --porcelain=v2 &&
+
+       test_sparse_match git read-tree -mu --no-sparse-checkout rename-out-to-out &&
+       test_sparse_match git status --porcelain=v2 &&
+       test_cmp sparse-checkout/folder2/0/1 sparse-index/folder2/0/1
+'
+
 test_expect_success 'merge, cherry-pick, and rebase' '
        init_repos &&

--
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