Implement 'git reset --patch'

This introduces a --patch mode for git-reset.  The basic case is

  git reset --patch -- [files...]

which acts as the opposite of 'git add --patch -- [files...]': it
offers hunks for *un*staging.  Advanced usage is

  git reset --patch <revision> -- [files...]

which offers hunks from the diff between the index and <revision> for
forward application to the index.  (That is, the basic case is just
<revision> = HEAD.)

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 69 insertions, 0 deletions

diff --git a/t/t7105-reset-patch.sh b/t/t7105-reset-patch.sh
new file mode 100755
index 000000000..c1f4fc3c6
--- /dev/null
+++ b/t/t7105-reset-patch.sh
@@ -0,0 +1,69 @@
+#!/bin/sh
+
+test_description='git reset --patch'
+. ./lib-patch-mode.sh
+
+test_expect_success 'setup' '
+	mkdir dir &&
+	echo parent > dir/foo &&
+	echo dummy > bar &&
+	git add dir &&
+	git commit -m initial &&
+	test_tick &&
+	test_commit second dir/foo head &&
+	set_and_save_state bar bar_work bar_index &&
+	save_head
+'
+
+# note: bar sorts before foo, so the first 'n' is always to skip 'bar'
+
+test_expect_success 'saying "n" does nothing' '
+	set_and_save_state dir/foo work work
+	(echo n; echo n) | git reset -p &&
+	verify_saved_state dir/foo &&
+	verify_saved_state bar
+'
+
+test_expect_success 'git reset -p' '
+	(echo n; echo y) | git reset -p &&
+	verify_state dir/foo work head &&
+	verify_saved_state bar
+'
+
+test_expect_success 'git reset -p HEAD^' '
+	(echo n; echo y) | git reset -p HEAD^ &&
+	verify_state dir/foo work parent &&
+	verify_saved_state bar
+'
+
+# The idea in the rest is that bar sorts first, so we always say 'y'
+# first and if the path limiter fails it'll apply to bar instead of
+# dir/foo.  There's always an extra 'n' to reject edits to dir/foo in
+# the failure case (and thus get out of the loop).
+
+test_expect_success 'git reset -p dir' '
+	set_state dir/foo work work
+	(echo y; echo n) | git reset -p dir &&
+	verify_state dir/foo work head &&
+	verify_saved_state bar
+'
+
+test_expect_success 'git reset -p -- foo (inside dir)' '
+	set_state dir/foo work work
+	(echo y; echo n) | (cd dir && git reset -p -- foo) &&
+	verify_state dir/foo work head &&
+	verify_saved_state bar
+'
+
+test_expect_success 'git reset -p HEAD^ -- dir' '
+	(echo y; echo n) | git reset -p HEAD^ -- dir &&
+	verify_state dir/foo work parent &&
+	verify_saved_state bar
+'
+
+test_expect_success 'none of this moved HEAD' '
+	verify_saved_head
+'
+
+
+test_done