format-patch: add --interdiff option to embed diff in cover letter
When submitting a revised version of a patch series, it can be helpful
(to reviewers) to include a summary of changes since the previous
attempt in the form of an interdiff, however, doing so involves manually
copy/pasting the diff into the cover letter.
Add an --interdiff option to automate this process. The argument to
--interdiff specifies the tip of the previous attempt against which to
generate the interdiff. For example:
git format-patch --cover-letter --interdiff=v1 -3 v2
The previous attempt and the patch series being formatted must share a
common base.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 53880da..57b4632 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -1717,4 +1717,21 @@
test_cmp expect actual
'
+test_expect_success 'interdiff: setup' '
+ git checkout -b boop master &&
+ test_commit fnorp blorp &&
+ test_commit fleep blorp
+'
+
+test_expect_success 'interdiff: cover-letter' '
+ sed "y/q/ /" >expect <<-\EOF &&
+ +fleep
+ --q
+ EOF
+ git format-patch --cover-letter --interdiff=boop~2 -1 boop &&
+ test_i18ngrep "^Interdiff:$" 0000-cover-letter.patch &&
+ sed "1,/^@@ /d; /^-- $/q" <0000-cover-letter.patch >actual &&
+ test_cmp expect actual
+'
+
test_done
