merge: add config option for verifySignatures

git merge --verify-signatures can be used to verify that the tip commit
of the branch being merged in is properly signed, but it's cumbersome to
have to specify that every time.

Add a configuration option that enables this behaviour by default, which
can be overridden by --no-verify-signatures.
Signed-off-by: NHans Jerry Illikainen <hji@dyntopia.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/merge-config.txt

@@ -26,6 +26,10 @@ merge.ff::
 	allowed (equivalent to giving the `--ff-only` option from the
 	command line).
 
+merge.verifySignatures::
+	If true, this is equivalent to the --verify-signatures command
+	line option. See linkgit:git-merge[1] for details.
+
 include::fmt-merge-msg-config.txt[]
 
 merge.renameLimit::

builtin/merge.c

@@ -567,6 +567,8 @@ static int git_merge_config(const char *k, const char *v, void *cb)
 
 	if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 		show_diffstat = git_config_bool(k, v);
+	else if (!strcmp(k, "merge.verifysignatures"))
+		verify_signatures = git_config_bool(k, v);
 	else if (!strcmp(k, "pull.twohead"))
 		return git_config_string(&pull_twohead, k, v);
 	else if (!strcmp(k, "pull.octopus"))

t/t7612-merge-verify-signatures.sh

@@ -39,23 +39,62 @@ test_expect_success GPG 'merge unsigned commit with verification' '
 	test_i18ngrep "does not have a GPG signature" mergeerror
 '
 
+test_expect_success GPG 'merge unsigned commit with merge.verifySignatures=true' '
+	test_config merge.verifySignatures true &&
+	test_must_fail git merge --ff-only side-unsigned 2>mergeerror &&
+	test_i18ngrep "does not have a GPG signature" mergeerror
+'
+
 test_expect_success GPG 'merge commit with bad signature with verification' '
 	test_must_fail git merge --ff-only --verify-signatures $(cat forged.commit) 2>mergeerror &&
 	test_i18ngrep "has a bad GPG signature" mergeerror
 '
 
+test_expect_success GPG 'merge commit with bad signature with merge.verifySignatures=true' '
+	test_config merge.verifySignatures true &&
+	test_must_fail git merge --ff-only $(cat forged.commit) 2>mergeerror &&
+	test_i18ngrep "has a bad GPG signature" mergeerror
+'
+
 test_expect_success GPG 'merge commit with untrusted signature with verification' '
 	test_must_fail git merge --ff-only --verify-signatures side-untrusted 2>mergeerror &&
 	test_i18ngrep "has an untrusted GPG signature" mergeerror
 '
 
+test_expect_success GPG 'merge commit with untrusted signature with merge.verifySignatures=true' '
+	test_config merge.verifySignatures true &&
+	test_must_fail git merge --ff-only side-untrusted 2>mergeerror &&
+	test_i18ngrep "has an untrusted GPG signature" mergeerror
+'
+
 test_expect_success GPG 'merge signed commit with verification' '
+	test_when_finished "git checkout initial" &&
 	git merge --verbose --ff-only --verify-signatures side-signed >mergeoutput &&
 	test_i18ngrep "has a good GPG signature" mergeoutput
 '
 
+test_expect_success GPG 'merge signed commit with merge.verifySignatures=true' '
+	test_when_finished "git checkout initial" &&
+	test_config merge.verifySignatures true &&
+	git merge --verbose --ff-only side-signed >mergeoutput &&
+	test_i18ngrep "has a good GPG signature" mergeoutput
+'
+
 test_expect_success GPG 'merge commit with bad signature without verification' '
+	test_when_finished "git checkout initial" &&
+	git merge $(cat forged.commit)
+'
+
+test_expect_success GPG 'merge commit with bad signature with merge.verifySignatures=false' '
+	test_when_finished "git checkout initial" &&
+	test_config merge.verifySignatures false &&
 	git merge $(cat forged.commit)
 '
 
+test_expect_success GPG 'merge commit with bad signature with merge.verifySignatures=true and --no-verify-signatures' '
+	test_when_finished "git checkout initial" &&
+	test_config merge.verifySignatures true &&
+	git merge --no-verify-signatures $(cat forged.commit)
+'
+
 test_done