am: fix signoff when other trailers are present

If there was no 'Signed-off-by:' trailer but another trailer such as
'Reported-by:' then 'git am --signoff' would add a blank line between
the existing trailers and the added 'Signed-off-by:' line. e.g.

    Rebase accepts '--rerere-autoupdate' as an option but only honors
    it if '-m' is also given. Fix it for a non-interactive rebase by
    passing on the option to 'git am' and 'git cherry-pick'.

    Reported-by: Junio C Hamano <gitster@pobox.com>

    Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>

Fix by using the code provided for this purpose in sequencer.c.
Change the tests so that they check the formatting of the
'Signed-off-by:' lines rather than just grepping for them.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/am.c

@@ -1188,34 +1188,10 @@ static void NORETURN die_user_resolve(const struct am_state *state)
  */
 static void am_append_signoff(struct am_state *state)
 {
-	char *cp;
-	struct strbuf mine = STRBUF_INIT;
 	struct strbuf sb = STRBUF_INIT;
 
 	strbuf_attach(&sb, state->msg, state->msg_len, state->msg_len);
-
+	append_signoff(&sb, 0, 0);
-	/* our sign-off */
-	strbuf_addf(&mine, "\n%s%s\n",
-		    sign_off_header,
-		    fmt_name(getenv("GIT_COMMITTER_NAME"),
-			     getenv("GIT_COMMITTER_EMAIL")));
-
-	/* Does sb end with it already? */
-	if (mine.len < sb.len &&
-	    !strcmp(mine.buf, sb.buf + sb.len - mine.len))
-		goto exit; /* no need to duplicate */
-
-	/* Does it have any Signed-off-by: in the text */
-	for (cp = sb.buf;
-	     cp && *cp && (cp = strstr(cp, sign_off_header)) != NULL;
-	     cp = strchr(cp, '\n')) {
-		if (sb.buf == cp || cp[-1] == '\n')
-			break;
-	}
-
-	strbuf_addstr(&sb, mine.buf + !!cp);
-exit:
-	strbuf_release(&mine);
 	state->msg = strbuf_detach(&sb, &state->msg_len);
 }
 

t/t4150-am.sh

@@ -40,6 +40,8 @@ test_expect_success 'setup: messages' '
 	dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio
 	dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te
 	feugait nulla facilisi.
+
+	Reported-by: A N Other <a.n.other@example.com>
 	EOF
 
 	cat >failmail <<-\EOF &&
@@ -93,7 +95,7 @@ test_expect_success setup '
 	echo world >>file &&
 	git add file &&
 	test_tick &&
-	git commit -s -F msg &&
+	git commit -F msg &&
 	git tag second &&
 
 	git format-patch --stdout first >patch1 &&
@@ -124,8 +126,6 @@ test_expect_success setup '
 		echo "Date: $GIT_AUTHOR_DATE" &&
 		echo &&
 		sed -e "1,2d" msg &&
-		echo &&
-		echo "Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>" &&
 		echo "---" &&
 		git diff-tree --no-commit-id --stat -p second
 	} >patch1-stgit.eml &&
@@ -144,8 +144,6 @@ test_expect_success setup '
 		echo "# Parent  $_z40" &&
 		cat msg &&
 		echo &&
-		echo "Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>" &&
-		echo &&
 		git diff-tree --no-commit-id -p second
 	} >patch1-hg.eml &&
 
@@ -470,13 +468,15 @@ test_expect_success 'am --signoff adds Signed-off-by: line' '
 	git reset --hard &&
 	git checkout -b master2 first &&
 	git am --signoff <patch2 &&
-	printf "%s\n" "$signoff" >expected &&
+	{
-	echo "Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>" >>expected &&
+		printf "third\n\nSigned-off-by: %s <%s>\n\n" \
-	git cat-file commit HEAD^ | grep "Signed-off-by:" >actual &&
+			"$GIT_COMMITTER_NAME" "$GIT_COMMITTER_EMAIL" &&
-	test_cmp expected actual &&
+		cat msg &&
-	echo "Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>" >expected &&
+		printf "Signed-off-by: %s <%s>\n\n" \
-	git cat-file commit HEAD | grep "Signed-off-by:" >actual &&
+			"$GIT_COMMITTER_NAME" "$GIT_COMMITTER_EMAIL"
-	test_cmp expected actual
+	} >expected-log &&
+	git log --pretty=%B -2 HEAD >actual &&
+	test_cmp expected-log actual
 '
 
 test_expect_success 'am stays in branch' '
@@ -486,17 +486,60 @@ test_expect_success 'am stays in branch' '
 '
 
 test_expect_success 'am --signoff does not add Signed-off-by: line if already there' '
-	git format-patch --stdout HEAD^ >patch3 &&
+	git format-patch --stdout first >patch3 &&
-	sed -e "/^Subject/ s,\[PATCH,Re: Re: Re: & 1/5 v2] [foo," patch3 >patch4 &&
+	git reset --hard first &&
-	rm -fr .git/rebase-apply &&
+	git am --signoff <patch3 &&
-	git reset --hard &&
+	git log --pretty=%B -2 HEAD >actual &&
-	git checkout HEAD^ &&
+	test_cmp expected-log actual
-	git am --signoff patch4 &&
+'
-	git cat-file commit HEAD >actual &&
+
-	test $(grep -c "^Signed-off-by:" actual) -eq 1
+test_expect_success 'am --signoff adds Signed-off-by: if another author is preset' '
+	NAME="A N Other" &&
+	EMAIL="a.n.other@example.com" &&
+	{
+		printf "third\n\nSigned-off-by: %s <%s>\nSigned-off-by: %s <%s>\n\n" \
+			"$GIT_COMMITTER_NAME" "$GIT_COMMITTER_EMAIL" \
+			"$NAME" "$EMAIL" &&
+		cat msg &&
+		printf "Signed-off-by: %s <%s>\nSigned-off-by: %s <%s>\n\n" \
+			"$GIT_COMMITTER_NAME" "$GIT_COMMITTER_EMAIL" \
+			"$NAME" "$EMAIL"
+	} >expected-log &&
+	git reset --hard first &&
+	GIT_COMMITTER_NAME="$NAME" GIT_COMMITTER_EMAIL="$EMAIL" \
+		git am --signoff <patch3 &&
+	git log --pretty=%B -2 HEAD >actual &&
+	test_cmp expected-log actual
+'
+
+test_expect_success 'am --signoff duplicates Signed-off-by: if it is not the last one' '
+	NAME="A N Other" &&
+	EMAIL="a.n.other@example.com" &&
+	{
+		printf "third\n\nSigned-off-by: %s <%s>\n\
+Signed-off-by: %s <%s>\nSigned-off-by: %s <%s>\n\n" \
+			"$GIT_COMMITTER_NAME" "$GIT_COMMITTER_EMAIL" \
+			"$NAME" "$EMAIL" \
+			"$GIT_COMMITTER_NAME" "$GIT_COMMITTER_EMAIL" &&
+		cat msg &&
+		printf "Signed-off-by: %s <%s>\nSigned-off-by: %s <%s>\n\
+Signed-off-by: %s <%s>\n\n" \
+			"$GIT_COMMITTER_NAME" "$GIT_COMMITTER_EMAIL" \
+			"$NAME" "$EMAIL" \
+			"$GIT_COMMITTER_NAME" "$GIT_COMMITTER_EMAIL"
+	} >expected-log &&
+	git format-patch --stdout first >patch3 &&
+	git reset --hard first &&
+	git am --signoff <patch3 &&
+	git log --pretty=%B -2 HEAD >actual &&
+	test_cmp expected-log actual
 '
 
 test_expect_success 'am without --keep removes Re: and [PATCH] stuff' '
+	git format-patch --stdout HEAD^ >tmp &&
+	sed -e "/^Subject/ s,\[PATCH,Re: Re: Re: & 1/5 v2] [foo," tmp >patch4 &&
+	git reset --hard HEAD^ &&
+	git am <patch4 &&
 	git rev-parse HEAD >expected &&
 	git rev-parse master2 >actual &&
 	test_cmp expected actual