[PATCH v4 2/2] commit-tree: add missing --gpg-sign flag

[Brandon Richardson <brandon1024.br@gmail.com>]

Add --gpg-sign option in commit-tree, which was documented, but not
implemented, in 55ca3f99ae. Add tests for the --gpg-sign option.

Signed-off-by: Brandon Richardson <brandon1024.br@gmail.com>
---
 builtin/commit-tree.c    |  8 +++++++-
 t/t7510-signed-commit.sh | 15 ++++++++++++---
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/builtin/commit-tree.c b/builtin/commit-tree.c
index 9ec36a82b..12cc403bd 100644
--- a/builtin/commit-tree.c
+++ b/builtin/commit-tree.c
@@ -66,7 +66,13 @@ int cmd_commit_tree(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 
-		if (skip_prefix(arg, "-S", &sign_commit))
+		if (!strcmp(arg, "--gpg-sign")) {
+		    sign_commit = "";
+		    continue;
+		}
+
+		if (skip_prefix(arg, "-S", &sign_commit) ||
+			skip_prefix(arg, "--gpg-sign=", &sign_commit))
 			continue;
 
 		if (!strcmp(arg, "--no-gpg-sign")) {
diff --git a/t/t7510-signed-commit.sh b/t/t7510-signed-commit.sh
index 58f528b98..682b23a06 100755
--- a/t/t7510-signed-commit.sh
+++ b/t/t7510-signed-commit.sh
@@ -55,13 +55,22 @@ test_expect_success GPG 'create signed commits' '
 	# explicit -S of course must sign.
 	echo 10 | git commit-tree -S HEAD^{tree} >oid &&
 	test_line_count = 1 oid &&
-	git tag tenth-signed $(cat oid)
+	git tag tenth-signed $(cat oid) &&
+
+	# --gpg-sign[=<key-id>] must sign.
+	echo 11 | git commit-tree --gpg-sign HEAD^{tree} >oid &&
+	test_line_count = 1 oid &&
+	git tag eleventh-signed $(cat oid) &&
+	echo 12 | git commit-tree --gpg-sign=B7227189 HEAD^{tree} >oid &&
+	test_line_count = 1 oid &&
+	git tag twelfth-signed-alt $(cat oid)
 '
 
 test_expect_success GPG 'verify and show signatures' '
 	(
 		for commit in initial second merge fourth-signed \
-			fifth-signed sixth-signed seventh-signed tenth-signed
+			fifth-signed sixth-signed seventh-signed tenth-signed \
+			eleventh-signed
 		do
 			git verify-commit $commit &&
 			git show --pretty=short --show-signature $commit >actual &&
@@ -82,7 +91,7 @@ test_expect_success GPG 'verify and show signatures' '
 		done
 	) &&
 	(
-		for commit in eighth-signed-alt
+		for commit in eighth-signed-alt twelfth-signed-alt
 		do
 			git show --pretty=short --show-signature $commit >actual &&
 			grep "Good signature from" actual &&
-- 
2.20.1