t/t7030-verify-tag: Add --format specifier tests

Verify-tag now provides --format specifiers to inspect and ensure the
contents of the tag are proper. We add two tests to ensure this
functionality works as expected: the return value should indicate if
verification passed, and the format specifiers must be respected.

Signed-off-by: Santiago Torres <santiago@nyu.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7030-verify-tag.sh

@@ -125,4 +125,20 @@ test_expect_success GPG 'verify multiple tags' '
 	test_cmp expect.stderr actual.stderr
 '
 
+test_expect_success 'verifying tag with --format' '
+	cat >expect <<-\EOF
+	tagname : fourth-signed
+	EOF &&
+	git verify-tag --format="tagname : %(tag)" "fourth-signed" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'verifying a forged tag with --format fail and format accordingly' '
+	cat >expect <<-\EOF
+	tagname : 7th forged-signed
+	EOF &&
+	test_must_fail git verify-tag --format="tagname : %(tag)" $(cat forged1.tag) >actual-forged &&
+	test_cmp expect actual-forged
+'
+
 test_done