git-add--interactive: manual hunk editing mode

Adds a new option 'e' to the 'add -p' command loop that lets you edit
the current hunk in your favourite editor.

If the resulting patch applies cleanly, the edited hunk will
immediately be marked for staging. If it does not apply cleanly, you
will be given an opportunity to edit again. If all lines of the hunk
are removed, then the edit is aborted and the hunk is left unchanged.

Applying the changed hunk(s) relies on Johannes Schindelin's new
--recount option for git-apply.

Note that the "real patch" test intentionally uses
  (echo e; echo n; echo d) | git add -p
even though the 'n' and 'd' are superfluous at first sight.  They
serve to get out of the interaction loop if git add -p wrongly
concludes the patch does not apply.

Many thanks to Jeff King <peff@peff.net> for lots of help and
suggestions.

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

1 files changed, 67 insertions, 0 deletions

diff --git a/t/t3701-add-interactive.sh b/t/t3701-add-interactive.sh
index fae64eae9f..e95663d8e6 100755
--- a/t/t3701-add-interactive.sh
+++ b/t/t3701-add-interactive.sh
@@ -66,6 +66,73 @@ test_expect_success 'revert works (commit)' '
 	grep "unchanged *+3/-0 file" output
 '
 
+cat >expected <<EOF
+EOF
+cat >fake_editor.sh <<EOF
+EOF
+chmod a+x fake_editor.sh
+test_set_editor "$(pwd)/fake_editor.sh"
+test_expect_success 'dummy edit works' '
+	(echo e; echo a) | git add -p &&
+	git diff > diff &&
+	test_cmp expected diff
+'
+
+cat >patch <<EOF
+@@ -1,1 +1,4 @@
+ this
++patch
+-doesn't
+ apply
+EOF
+echo "#!$SHELL_PATH" >fake_editor.sh
+cat >>fake_editor.sh <<\EOF
+mv -f "$1" oldpatch &&
+mv -f patch "$1"
+EOF
+chmod a+x fake_editor.sh
+test_set_editor "$(pwd)/fake_editor.sh"
+test_expect_success 'bad edit rejected' '
+	git reset &&
+	(echo e; echo n; echo d) | git add -p >output &&
+	grep "hunk does not apply" output
+'
+
+cat >patch <<EOF
+this patch
+is garbage
+EOF
+test_expect_success 'garbage edit rejected' '
+	git reset &&
+	(echo e; echo n; echo d) | git add -p >output &&
+	grep "hunk does not apply" output
+'
+
+cat >patch <<EOF
+@@ -1,0 +1,0 @@
+ baseline
++content
++newcontent
++lines
+EOF
+cat >expected <<EOF
+diff --git a/file b/file
+index b5dd6c9..f910ae9 100644
+--- a/file
++++ b/file
+@@ -1,4 +1,4 @@
+ baseline
+ content
+-newcontent
++more
+ lines
+EOF
+test_expect_success 'real edit works' '
+	(echo e; echo n; echo d) | git add -p &&
+	git diff >output &&
+	test_cmp expected output
+'
+
 if test "$(git config --bool core.filemode)" = false
 then
     say 'skipping filemode tests (filesystem does not properly support modes)'