rebase--interactive: fix parent rewriting for dropped commits

`rebase -i -p` got its rev-list of commits to keep by --left-right and
--cherry-pick. Adding --cherry-pick would drop commits that duplicated changes
already in the rebase target.

The dropped commits were then forgotten about when it came to rewriting the
parents of their descendents, so the descendents would get cherry-picked with
their old, unwritten parents and essentially make the rebase a no-op.

This commit adds a $DOTEST/dropped directory to remember dropped commits and
rewrite their children's parent as the dropped commit's possibly-rewritten
first-parent.

Signed-off-by: Stephen Haberman <stephen@exigencecorp.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

1 files changed, 139 insertions, 0 deletions

diff --git a/t/t3410-rebase-preserve-dropped-merges.sh b/t/t3410-rebase-preserve-dropped-merges.sh
new file mode 100755
index 0000000000..5816415aaf
--- /dev/null
+++ b/t/t3410-rebase-preserve-dropped-merges.sh
@@ -0,0 +1,139 @@
+#!/bin/sh
+#
+# Copyright (c) 2008 Stephen Haberman
+#
+
+test_description='git rebase preserve merges
+
+This test runs git rebase with preserve merges and ensures commits
+dropped by the --cherry-pick flag have their childrens parents
+rewritten.
+'
+. ./test-lib.sh
+
+# set up two branches like this:
+#
+# A - B - C - D - E
+#   \
+#     F - G - H
+#       \
+#         I
+#
+# where B, D and G touch the same file.
+
+test_expect_success 'setup' '
+	: > file1 &&
+	git add file1 &&
+	test_tick &&
+	git commit -m A &&
+	git tag A &&
+	echo 1 > file1 &&
+	test_tick &&
+	git commit -m B file1 &&
+	: > file2 &&
+	git add file2 &&
+	test_tick &&
+	git commit -m C &&
+	echo 2 > file1 &&
+	test_tick &&
+	git commit -m D file1 &&
+	: > file3 &&
+	git add file3 &&
+	test_tick &&
+	git commit -m E &&
+	git tag E &&
+	git checkout -b branch1 A &&
+	: > file4 &&
+	git add file4 &&
+	test_tick &&
+	git commit -m F &&
+	git tag F &&
+	echo 3 > file1 &&
+	test_tick &&
+	git commit -m G file1 &&
+	git tag G &&
+	: > file5 &&
+	git add file5 &&
+	test_tick &&
+	git commit -m H &&
+	git tag H &&
+	git checkout -b branch2 F &&
+	: > file6 &&
+	git add file6 &&
+	test_tick &&
+	git commit -m I &&
+	git tag I
+'
+
+# A - B - C - D - E
+#   \             \ \
+#     F - G - H -- L \        -->   L
+#       \            |               \
+#         I -- G2 -- J -- K           I -- K
+# G2 = same changes as G
+test_expect_success 'skip same-resolution merges with -p' '
+	git checkout branch1 &&
+	! git merge E &&
+	echo 23 > file1 &&
+	git add file1 &&
+	git commit -m L &&
+	git checkout branch2 &&
+	echo 3 > file1 &&
+	git commit -a -m G2 &&
+	! git merge E &&
+	echo 23 > file1 &&
+	git add file1 &&
+	git commit -m J &&
+	echo file7 > file7 &&
+	git add file7 &&
+	git commit -m K &&
+	GIT_EDITOR=: git rebase -i -p branch1 &&
+	test $(git rev-parse branch2^^) = $(git rev-parse branch1) &&
+	test "23" = "$(cat file1)" &&
+	test "" = "$(cat file6)" &&
+	test "file7" = "$(cat file7)" &&
+
+	git checkout branch1 &&
+	git reset --hard H &&
+	git checkout branch2 &&
+	git reset --hard I
+'
+
+# A - B - C - D - E
+#   \             \ \
+#     F - G - H -- L \        -->   L
+#       \            |               \
+#         I -- G2 -- J -- K           I -- G2 -- K
+# G2 = different changes as G
+test_expect_success 'keep different-resolution merges with -p' '
+	git checkout branch1 &&
+	! git merge E &&
+	echo 23 > file1 &&
+	git add file1 &&
+	git commit -m L &&
+	git checkout branch2 &&
+	echo 4 > file1 &&
+	git commit -a -m G2 &&
+	! git merge E &&
+	echo 24 > file1 &&
+	git add file1 &&
+	git commit -m J &&
+	echo file7 > file7 &&
+	git add file7 &&
+	git commit -m K &&
+	! GIT_EDITOR=: git rebase -i -p branch1 &&
+	echo 234 > file1 &&
+	git add file1 &&
+	GIT_EDITOR=: git rebase --continue &&
+	test $(git rev-parse branch2^^^) = $(git rev-parse branch1) &&
+	test "234" = "$(cat file1)" &&
+	test "" = "$(cat file6)" &&
+	test "file7" = "$(cat file7)" &&
+
+	git checkout branch1 &&
+	git reset --hard H &&
+	git checkout branch2 &&
+	git reset --hard I
+'
+
+test_done