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diff --git a/t/t3427-rebase-subtree.sh b/t/t3427-rebase-subtree.sh
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+++ b/t/t3427-rebase-subtree.sh
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+#!/bin/sh
+
+test_description='git rebase tests for -Xsubtree
+
+This test runs git rebase and tests the subtree strategy.
+'
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-rebase.sh
+
+commit_message() {
+	git log --pretty=format:%s -1 "$1"
+}
+
+# There are a few bugs in the rebase with regards to the subtree strategy, and
+# this test script tries to document them.  First, the following commit history
+# is generated (the onelines are shown, time flows from left to right):
+#
+# topic_1 - topic_2 - topic_3
+#                             \
+# README ---------------------- Add subproject main - topic_4 - files_subtree/topic_5
+#
+# Where the merge moves the files topic_[123].t into the subdirectory
+# files_subtree/ and topic_4 as well as files_subtree/topic_5 add files to that
+# directory directly.
+#
+# Then, in subsequent test cases, `git filter-branch` is used to distill just
+# the commits that touch files_subtree/. To give it a final pre-rebase touch,
+# an empty commit is added on top. The pre-rebase commit history looks like
+# this:
+#
+# Add subproject main - topic_4 - files_subtree/topic_5 - Empty commit
+#
+# where the root commit adds three files: topic_1.t, topic_2.t and topic_3.t.
+#
+# This commit history is then rebased onto `topic_3` with the
+# `-Xsubtree=files_subtree` option in two different ways:
+#
+# 1. without specifying a rebase backend
+# 2. using the `--rebase-merges` backend
+
+test_expect_success 'setup' '
+	test_commit README &&
+
+	git init files &&
+	test_commit -C files topic_1 &&
+	test_commit -C files topic_2 &&
+	test_commit -C files topic_3 &&
+
+	: perform subtree merge into files_subtree/ &&
+	git fetch files refs/heads/main:refs/heads/files-main &&
+	git merge -s ours --no-commit --allow-unrelated-histories \
+		files-main &&
+	git read-tree --prefix=files_subtree -u files-main &&
+	git commit -m "Add subproject main" &&
+
+	: add two extra commits to rebase &&
+	test_commit -C files_subtree topic_4 &&
+	test_commit files_subtree/topic_5 &&
+
+	git checkout -b to-rebase &&
+	git fast-export --no-data HEAD -- files_subtree/ |
+		sed -e "s%\([0-9a-f]\{40\} \)files_subtree/%\1%" |
+		git fast-import --force --quiet &&
+	git reset --hard &&
+	git commit -m "Empty commit" --allow-empty
+'
+
+test_expect_success 'Rebase -Xsubtree --empty=ask --onto commit' '
+	reset_rebase &&
+	git checkout -b rebase-onto to-rebase &&
+	test_must_fail git rebase -Xsubtree=files_subtree --empty=ask --onto files-main main &&
+	: first pick results in no changes &&
+	git rebase --skip &&
+	verbose test "$(commit_message HEAD~2)" = "topic_4" &&
+	verbose test "$(commit_message HEAD~)" = "files_subtree/topic_5" &&
+	verbose test "$(commit_message HEAD)" = "Empty commit"
+'
+
+test_expect_success 'Rebase -Xsubtree --empty=ask --rebase-merges --onto commit' '
+	reset_rebase &&
+	git checkout -b rebase-merges-onto to-rebase &&
+	test_must_fail git rebase -Xsubtree=files_subtree --empty=ask --rebase-merges --onto files-main --root &&
+	: first pick results in no changes &&
+	git rebase --skip &&
+	verbose test "$(commit_message HEAD~2)" = "topic_4" &&
+	verbose test "$(commit_message HEAD~)" = "files_subtree/topic_5" &&
+	verbose test "$(commit_message HEAD)" = "Empty commit"
+'
+
+test_done