tests: add message trailer parsing test cases

tests/message/trailer.c

+#include "clar_libgit2.h"
+#include "message.h"
+
+struct trailer {
+	const char *key;
+	const char *value;
+};
+
+struct cb_state {
+	struct trailer *trailer;
+};
+
+static int trailer_cb(const char *key, const char *value, void *st_)
+{
+	struct cb_state *st = st_;
+
+	cl_assert_equal_s(st->trailer->key, key);
+	cl_assert_equal_s(st->trailer->value, value);
+
+	st->trailer++;
+
+	return 0;
+}
+
+static void assert_trailers(const char *message, struct trailer *trailers)
+{
+	struct cb_state st = { trailers };
+
+	int rc = git_message_trailers(message, trailer_cb, &st);
+
+	cl_assert_equal_s(NULL, st.trailer->key);
+	cl_assert_equal_s(NULL, st.trailer->value);
+
+	cl_assert_equal_i(0, rc);
+}
+
+void test_message_trailer__simple(void)
+{
+	assert_trailers(
+		"Message\n"
+		"\n"
+		"Signed-off-by: foo@bar.com\n"
+		"Signed-off-by: someone@else.com\n"
+	,
+		(struct trailer[]){
+			{ "Signed-off-by", "foo@bar.com" },
+			{ "Signed-off-by", "someone@else.com" },
+			{ NULL, NULL },
+		}
+	);
+}
+
+void test_message_trailer__no_whitespace(void)
+{
+	assert_trailers(
+		"Message\n"
+		"\n"
+		"Key:value\n"
+	,
+		(struct trailer[]){
+			{ "Key", "value" },
+			{ NULL, NULL },
+		}
+	);
+}
+
+void test_message_trailer__extra_whitespace(void)
+{
+	assert_trailers(
+		"Message\n"
+		"\n"
+		"Key   :   value\n"
+	,
+		(struct trailer[]){
+			{ "Key", "value" },
+			{ NULL, NULL },
+		}
+	);
+}
+
+void test_message_trailer__no_newline(void)
+{
+	assert_trailers(
+		"Message\n"
+		"\n"
+		"Key: value"
+	,
+		(struct trailer[]){
+			{ "Key", "value" },
+			{ NULL, NULL },
+		}
+	);
+}
+
+void test_message_trailer__not_last_paragraph(void)
+{
+	assert_trailers(
+		"Message\n"
+		"\n"
+		"Key: value\n"
+		"\n"
+		"More stuff\n"
+	,
+		(struct trailer[]){
+			{ NULL, NULL },
+		}
+	);
+}
+
+void test_message_trailer__conflicts(void)
+{
+	assert_trailers(
+		"Message\n"
+		"\n"
+		"Key: value\n"
+		"\n"
+		"Conflicts:\n"
+		"\tfoo.c\n"
+	,
+		(struct trailer[]){
+			{ "Key", "value" },
+			{ NULL, NULL },
+		}
+	);
+}
+
+void test_message_trailer__patch(void)
+{
+	assert_trailers(
+		"Message\n"
+		"\n"
+		"Key: value\n"
+		"\n"
+		"---\n"
+		"More: stuff\n"
+	,
+		(struct trailer[]){
+			{ "Key", "value" },
+			{ NULL, NULL },
+		}
+	);
+}
+
+void test_message_trailer__continuation(void)
+{
+	assert_trailers(
+		"Message\n"
+		"\n"
+		"A: b\n"
+		" c\n"
+		"D: e\n"
+		" f: g h\n"
+		"I: j\n"
+	,
+		(struct trailer[]){
+			{ "A", "b\n c" },
+			{ "D", "e\n f: g h" },
+			{ "I", "j" },
+			{ NULL, NULL },
+		}
+	);
+}
+
+void test_message_trailer__invalid(void)
+{
+	assert_trailers(
+		"Message\n"
+		"\n"
+		"Signed-off-by: some@one.com\n"
+		"Not a trailer\n"
+		"Another: trailer\n"
+	,
+		(struct trailer[]){
+			{ "Signed-off-by", "some@one.com" },
+			{ "Another", "trailer" },
+			{ NULL, NULL },
+		}
+	);
+}