revert: Save data for continuing after conflict resolution

Ever since v1.7.2-rc1~4^2~7 (revert: allow cherry-picking more than
one commit, 2010-06-02), a single invocation of "git cherry-pick" or
"git revert" can perform picks of several individual commits.  To
implement features like "--continue" to continue the whole operation,
we will need to store some information about the state and the plan at
the beginning.  Introduce a ".git/sequencer/head" file to store this
state, and ".git/sequencer/todo" file to store the plan.  The head
file contains the SHA-1 of the HEAD before the start of the operation,
and the todo file contains an instruction sheet whose format is
inspired by the format of the "rebase -i" instruction sheet.  As a
result, a typical todo file looks like:

  pick 8537f0e submodule add: test failure when url is not configured
  pick 4d68932 submodule add: allow relative repository path
  pick f22a17e submodule add: clean up duplicated code
  pick 59a5775 make copy_ref globally available

Since SHA-1 hex is abbreviated using an find_unique_abbrev(), it is
unambiguous.  This does not guarantee that there will be no ambiguity
when more objects are added to the repository.

These two files alone are not enough to implement a "--continue" that
remembers the command-line options specified; later patches in the
series save them too.

These new files are unrelated to the existing .git/CHERRY_PICK_HEAD,
which will still be useful while committing after a conflict
resolution.

Inspired-by: Christian Couder <chriscool@tuxfamily.org>
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/t/t3510-cherry-pick-sequence.sh b/t/t3510-cherry-pick-sequence.sh
new file mode 100755
index 000000000..a2c70ad4b
--- /dev/null
+++ b/t/t3510-cherry-pick-sequence.sh
@@ -0,0 +1,48 @@
+#!/bin/sh
+
+test_description='Test cherry-pick continuation features
+
+  + anotherpick: rewrites foo to d
+  + picked: rewrites foo to c
+  + unrelatedpick: rewrites unrelated to reallyunrelated
+  + base: rewrites foo to b
+  + initial: writes foo as a, unrelated as unrelated
+
+'
+
+. ./test-lib.sh
+
+pristine_detach () {
+	rm -rf .git/sequencer &&
+	git checkout -f "$1^0" &&
+	git read-tree -u --reset HEAD &&
+	git clean -d -f -f -q -x
+}
+
+test_expect_success setup '
+	echo unrelated >unrelated &&
+	git add unrelated &&
+	test_commit initial foo a &&
+	test_commit base foo b &&
+	test_commit unrelatedpick unrelated reallyunrelated &&
+	test_commit picked foo c &&
+	test_commit anotherpick foo d &&
+	git config advice.detachedhead false
+
+'
+
+test_expect_success 'cherry-pick persists data on failure' '
+	pristine_detach initial &&
+	test_must_fail git cherry-pick base..anotherpick &&
+	test_path_is_dir .git/sequencer &&
+	test_path_is_file .git/sequencer/head &&
+	test_path_is_file .git/sequencer/todo
+'
+
+test_expect_success 'cherry-pick cleans up sequencer state upon success' '
+	pristine_detach initial &&
+	git cherry-pick initial..picked &&
+	test_path_is_missing .git/sequencer
+'
+
+test_done